Pokemon cards!! - needs advice

Well, the basic rules of the TCG are not that difficult, but always try to memorize them because sometimes you can lose due to a small mistake that you don't even notice. And if you're going to participate in competitions, always be aware of which model is in rotation for the year. In case you don't know, at the beginning of each year (this year's hasn't come out yet, if I'm not mistaken), the Pokemon Company rotates some types of cards so that some old models can't be used. So always pay attention to that. For example, last year, only cards with the letters F, G, and H could be used, but some informal championships don't care much about that. And about the deck, if you're in doubt about building one, you can buy a ready-made one. I highly recommend the Charizard and Gardevoir ones, both of which are monotype. 

If you're only bothered about collecting id reccomend starting wth some of the smaller collections like obsidian flames because going after the main sets like prismatic eveolutions can be really expensive atm.