To start this section off I will give the 3 most common mistakes I see managers make and add the key reason to why so many people struggle to do well as a manager of a team consistently.
1. Too many big contracts, especially in term (aka length). The only reason you should give a player a contract longer than 3 season is because you can guarantee that they will be a major player on your team for the entirety of the contract from the moment they sign until the season that contract ends. Major being core of your offense, defense or #1 goalie that is exceptionally talented relative to your league. Everybody else you should be signing, and if you want resigning, to deals 1-3 seasons in length. A rule of thumb to use is having no more than 6 or so players with contracts longer than 3 seasons.
2. How young can you go? There are a number of managers that are obscenely obsessed with having a young team. I have seen a post before of a manager offering a 25yo player looking for a young player in return. 25 IS YOUNG! Yes you want some young players but you want some vets too. A veteran player gets a veteran experience bonus to their play making them typically play better than younger players of equal talent. At the same time players develop more the more they play. The key is striking a balance between youth and vets on your team. Keep in mind you also have draft picks that will turn into players every year. Even if you don't bother with the draft you are pretty much guaranteed to be getting 1 player than can make your roster in 3 seasons time. Having a roster full of young players is a potential disaster as you could be forced into letting go a young and talented player.
3. Role players are key. As much as you need offensively talented forwards you also need defensively talented ones as well. As much as you need defensively talented forwards you need defensive puck movers as well. I have seen one manager get as many of the top talented forwards as possible and not bother about D or goaltending. I have also seen a team with 4 lines of very good offensive forwards struggle because of no defensive forwards despite very good D and very good goalie. I have also seen a team that had 6 great defensive Dmen but could not pass the puck and again struggled. They were all missing key components that are needed to make a successful team. Something as "simple" as not having a handful of quality defensive forwards can make an otherwise top 6 talent team in a league finish bottom 6 in results. Just as important as having those key role players is also utilizing them correctly in your roster.
The one key reason players struggle with manager games is because they forget one key aspect of what a manager needs to do. Balance long term with short term. Too many managers focus on the current and very near future and it bites them big 3 or 4 seasons from then. This is most commonly seen in excessive youth movement teams and on teams that give out too many long term contracts.
Time for me to start on the bigger part of this. However before that a forward note. The most important thing has nothing to do with the players on your team, the tactics or anything in game really. It is all about you. More specifically you identifying what kind of team you want. What do you want the identity of your team to be? That is by far the most important thing. Do you want an all out speed team like the Pittsburgh Penguins? A physical team like the Boston Bruins? A skill possession team like the Montreal Canadiens? Without an identity for your team it is more likely to end up relying mostly on random luck for good seasons and looking mostly like the Edmonton Oilers of the past 6 or 7 seasons on a more long term basis. The big thing here is identifying what you want the identity of your team to be, to stick to it and never lose sight of it. The identity you create for your team is the foundation for your team and the basis of which everything else relies. The second most important thing is again you. Specifically you learning what you need to know.
Now that I have said that let us look at how that applies in the most obvious way to your team. Tactics. First and foremost the "core" tactics. The core tactics are the basis of how your team will play on the ice. These core tactics are all under the tactics section and are; Offensive tactic, Defensive tactic, Power play and Penalty kill. These dictate the foundations of how your team plays on the ice. You should choose them based upon what I said above regarding your chosen team identity. Also once you make a decision on what you will use stick to it as changing one of these will have profound negative impacts to the play of your team for an extended period until they get familiar with the new core tactic. So what is the difference between them and what kind of players skill wise do you need to make them work successfully?
Tactics disclaimer: I would love to get deep into the details of these tactics but honestly I can't. The tactics in this game have been simplified to a great deal to the point where multiple and very drastically different things are combined into the same categories. For example in the offensive section below almost every NHL team crashes the net and plays dump and chase to some degree while having a puck possession focused offense. Honestly though the tactics being this way is likely for the better for newer players so as not to overwhelm them.
Crash the Net: This is very simple. Puck and players to the net. In real life this isn't a tactic so much as it is a way of life. Hockey players are preached to crash the net. "Go to the net and good things will happen," "throw the puck to the net because anything could happen" and "there is no such thing as a bad shot" (there actually is) are things you commonly hear if you watch NHL games.
What do you need for this tactic? Players high in the physical attribute. Bigger sized players are also a plus. The good about this tactic: You only need one skill to make it work and it is very simple. The Bad: You NEED one skill to make it work or it will not work at all, it is heavily reliant on your players to have higher physical skills and be bigger than the opposing defensemen for it to work, it is simple and very easy to counter.
This tactic is the least efficient tactic out there and the most reliant on the opposing team being weak to it makes it pretty much not worth it. This tactic isn't garbage. it is just over reliant on a few things making it a very situational tactic at best. Using a situational tactic all of the time isn't exactly an ideal situation.
Dump and Chase: This is all about getting the puck deep and then getting the puck via a strong forecheck. This tactic is less about skill and more about the defensive posture of the opposing team through the neutral zone. If the defensive posture is "up" then a dump and chase is a very good tactic to use. However that is in a real hockey game.
What do you need for this tactic? Speed and physical skills predominantly. Like above bigger sized players are a plus. The good: This tactic is all about using your teams physical attributes to the greatest possible effect. It isn't overly reliant on puck skills. The bad: Due to the aggressive hitting nature of this tactic over aggressive players will take a lot of penalties, considering that your team will take more penalties off of the bat as it is that could really kill any momentum your team builds on a regular basis making it difficult for your team to generate much offense.
This tactic is still very reliant on a players physical skill so not having a lot of forwards with high physical ratings will hurt this offense a lot. This tactic and the tactic above are the two physically focused offensive styles. The dump and chase is the more versatile of the two as it is less reliant on the opponent and their skills and more about your own players and theirs.
Puck possession: This is all about controlling the puck in the opponents end by passing the puck around. This tactic is the basis of most modern hockey offenses. Even the LA Kings use a puck possession offense with a heavy influence of physical play whereas the Chicago Blackhawks use a more finesse based puck possession style.
What you need: Puck handling and passing and then more puck handling and passing and then even more. The Good: This tactic is all about the puck skills of your players. This is the most difficult offense to stop with a skilled team. The bad: This is the most difficult offense to run because it is exceptionally reliant on the puck skills of your players.
This tactic is very high risk high reward in nature. As a result if you don't do things right things can very easily go very wrong with this tactic. You don't need fast or physical players but that will definitely help.
Transition rushes: This is all about counter attacking quickly. Get the puck and get it up ice quickly trying to create odd man rushes. However in the real life game this is not an offensive strategy per se and more another part of the game altogether.
What you need: A lot of skating, passing and puck handling. The good: Very aggressive and fast offensive tactic that aims to take advantage of both the speed and skill of your players. The bad: This tactic has the most demands from the players as they need to be fast, good puck handlers and passers.
Like puck possession this is high risk high reward but it is also the tactic that demands the most out of the players which demands the most out of you as well as you need the right players for this tactic to work. Also this tactic has some reliance on the opposing team as well making it that much more harder to implement successfully.
Defensive tactics coming up hopefully shortly.