I know guys who have had 100k wins so it can happen, I prefer DraftKings because there's no kickers and you can change your lineup for later games after the early ones start. Sign up at rotogrinders.com and deposit through their link so you get all their research tools for free.
There are different types of games, I'll try to explain the differences and brief strategy.
Cash games-double ups, 50/50s, triple ups and head to head games. These you want guys with high floors, it doesn't matter if you finish first or 50th if the top fifty all get the same prize.
GPP-guaranteed prize pools. These are the lottery tickets so to speak. You need a big score to make money so you need to have guys that are not widely owned to have a shot at the top prize.
I usually go with a 80/20 split in favor of cash games to lower the weekly variance.