Well 1st off u need to pick 2 cans who u wanna work with thn build a deck using thm , save up for cards since u can buy credits use them to get full decks build your collection , sell the ones you don't need
Cheap cards usually sacrifice either damage for power or power for damage. I suggest you safe up so you don't have to compromise.
La Junta, but with only 500 clintz, you won't get all the cards
It depends on the deck, but La Junta cards are cheap and good
Fang also has pretty good damage, and not bad for stop ability, and stop bonus either, if you could finagle the good ones
but you're stretching if you plan on completing a good deck with such few clintz.