If looking to establish business credit with a business that you've already established, I would recommend the following:
Get an Account on Nav.com (free or paid)
Track Your Personal Credit for Free
Boost Your Personal Credit if Below 740 Before Business Applications
Know the Difference Between Corporate Cards and Small Business Cards.
Document Your Goals, Situation, & Current/Projected Spending To Help Know Which Cards Will be Best.
Do Some Online Research & Establish More Online Accounts Without Establishing Any Credit Cards or Loans
Get a Professional Consultation