I'm in two leagues. Just to point out how different things can be, in one league stolen bases count for 2 points and strikeouts are minus 1. In the other league, stolen bases are 1 point and strikeouts are -1/2 a point. So in the first league, guys who steal a lot of bases and don't strikeout have a lot more value than the other league. I can also take more chances on guys who have power but K a lot in the second league....harder to pull the trigger on that same type of boom/bust guy in the other league.
One league is head to head - meaning you play another guy in the league for a week and whoever has the most points at the end of the week "wins". You keep records and then there are a few weeks of playoffs at the end of the season.
The other league (which is rare) is total accumulated points. At the end of the years who ever has the most points total wins the league.
Then there are 5x5 leagues, which track 5 hitting and 5 pitching categories. Usually, it's batting average, runs, RBI, home runs, and steals for hitting and wins, strikeouts, saves, ERA, and WHIP for pitching. I've never played in one of those but you can see how the strategy is going to be different depending on league type.