Just don't play your shittier bench players all year long or you will get fucked.
Make sure you play your best players for all games possible, because if you bench them early and they get injured you end up fucking yourself.
Don't play every bench player every game because you will go over and your star players will have to be benched for the end of the season.
Goalies have more give because they definitely don't play every game of the season. A starting goalie might play 50-60 games a season, and the goalie allotment is 82 games per goalie, so if you have 3 goalies you can safely play all 3 all year and be close.
Another tip, that only really works if you are willing to spend the time on doing homework and keeping track of the NHL, is to match up players and goalies against certain teams when it makes sense. Say you have a starting goalie on a shitty team that is playing against a hot team with lots of scorers, might be good to bench that goalie that night. Same with players, if you have a benched forward playing against a shitty team with a shitty goalie, then it's a good time to pull him off your bench and try to get extra points.
Don't know why I'm helping you, ignore all of that. Play everyone every day no matter what.