My tip is to play some Daily Tournament to earn some more clintz, 50k is not much
there are many good clans in elo, just find a clan you like and start to invest in buying some of those characters
just pick any deck and give it a go
If you are creative you can make a great deck with common and uncommon cards. Usually the most expensive common cards will cost you 3000 clintz max. I used a Sentinel deck when I first started winning a lot. They are great at team damage, and Tobie is also excellent.