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Browse credit cards from a variety of issuers to see if there's a better card for you.
Bluevine and those places analyse your checking sales so if you are doing just $4k a month you will not receive $20k+ lines.
If you have good personal credit, your best best is just to apply for business credit cards. You will take the HP (unless you have a relationship with Amex and then no credit pull) and all business credit cards besides Capital One do not report to personal credit as long as you don't default.