Master of one (or two). Nobody can be expert in all sports. For example, my main focus is basketball. I'm not deep in football but I don't need to be a football expert to make money in football. I have friends (handicappers) who are good in football. If you try to cap all sports, you'll be master of none.
If you have to ask, then it is one. What are your win statistics in all the sports you cap? If you can win at two, then do two. BTW, totals and sides in the same sport, is two sports. And within each sport you should be keeping track off the main categories; sides: away and home wins, totals: overs and unders.
Crack one sport first, then a second, and so on. Then take it to the next level for one sport first, followed by a second, and so on. Repeat. You can never rest on your laurels. It takes time, but you can definitely gain an advantage in every sport you focus on.
The great thing about US sports is that they're year round and, with the exception of football, are played every day. NBA and MLB offer more opportunities than the NFL. NFL is most overanalyzed. If you can win in the NFL, you can win in the other leagues.
i win on soccer and horse racing consistently. Recently I take up basketball (NBA n WNBA) due to job requirement. Im not winning as much as the other two at this moment, but I believe it is due to knowledge rather than skill. So its not a bad thing to take up more sports. But not too many though! 7-8 leagues/comps. is the absolute max though.