Pick a handful of teams just based on first impressions, which usually come from players that you like for their skill and/or personality. Watch a few games for each team when the season starts (or games from last season if you have access to them) and you should click with a team pretty quickly.

Consider paying for the NBA streaming service, it lets you watch as much basketball as you want. I think you can sign up by the month if you just want to use it to get up to speed and that’ll give you access to all of last season’s games as well as a bunch of much older ones.