Establishing and buidling business credit with my existing LLC

I have a LLC for a tax preparation business I recently incorporated early this year, and also set up a business account as well. I want to eventually qualify for a business line of credit, and from my understanding it would be best to set up a dnb number, as well as setting up tradelines. My personal credit isnt so great at this time, but I am in the process of boosting it back up. But I also wanted to avoid doing a personal guarantee for a line of credit. Can anyone give any input on what would be advantageous?

Thanks