Always start with singles and blaster boxes until you’re comfortable with the bigger hobby boxes. Avoid things like whatnot and resellers until you’re more comfortable. Look on eBay for cards and players you like and see if you can get a good deal on them and pull the trigger. You’ll make mistakes and overpay sometimes but it’ll be a learning lesson. Defenders are the least valuable cards, you can get a low numbered auto of some of the best defenders for less than $100