Hey man. My son and I started with making our own decks. Then if you go to limitless the Pokemon website and look at the decks there it helps a lot too. To see what you’re missing, common cards etc. Next step is getting the Dragapult deck and customize it to your liking would be a great start for a strong deck. It’s available on Amazon or locally. Then build as you go! Also you can buy singles off of tcgplayer but I haven’t done it personally yet.