I think the first thing to decide is what format you like playing. Most people (including myself) start playing singles with Smogon's rules, and usually in the OU tier. However, I would suggest giving the VGC format a try as it is super fun and adds another layer of strategy compared to singles, as there are four pokemon on the field! It also means you can participate in local tournaments, which is always a lot of fun. Anyway, decide what format you want to play first. VM me if you need any help, I'd be happy to assist! :)