Once you have handed one back, don't just cut it up as they will keep charging you yearly fees if they don't know you don't want it any more. Also ask for the limit to be reduced if you don't need that amount.
We have a credit card with $500 limit so you can get them with low limits if need be.

When I had trouble getting the budget correct I started a spread sheet on the computer, before that I used a book, and it really helped as it was there in black & white what I was spending. It really helped to see where the money was going.
The best part was the saving column I started and enjoyed watching it grow bit by bit, sometimes only $5.00 a pay but it was still an encouragement to save.