As your credit gets dramatically better, say 50 points, you will find it easier to open up new and better Cap One cards than to try and build them up from a $500 CL. Seach Capital One "glass ceilings" and "buckets"
You may get some CLI, I got one for $8,000 once, but I also got approved for a $30k card the same day I was denied for ANY CLI on 3 accounts.
GL - YMMV
