Well... if you're talking about "credit", vendors can't do jack. Credit card companies do that. The best way is to charge stuff, and pay it all on time. That will start showing a track-record of you being responsible. Also a CD will help too, but that'll usually take about a year or so.
an easy thing to do is for purchases you'd normally pay cash for, just as jwingfield said, buy them on credit, and pay off right away. Start by applying for a low limit, and slowly building it up. Paying on time and keeping little to no balance is important. Especially since you are trying to BUILD credit, and not hurt your report, make sure to keep up on this. If you tend to get rejected at a lot of places because you haven't had any credit cards before, try starting somewhere small, or Sears. They are fairly open to new credit, and you can pick up small hand tools or supplies there. then build away.
hope this helps
If you have gone to the county clerks office and filed your DBA you will start receiving credit card apps from everyone for your business. I still receive up to 5 every week. I don't guess that they will ever stop trying.
Fleet business cards approve just about everybody goe to there online site and apply. Also get a gas card for the company. Speedway has a thing called superfleet. Also just talk around town and anyone you are friends with set up an account with their store. We set up our first credit at a hardway store very small in our town. Because when you apply for certain things they will ask for credit references. After one year in business I guarantee you wont have to worry about it. Alot of businesses dont like to give accounts to newbies thier first year since more then half die after a year. Specially our industry. If they see you around the second and you have bought alot of crap from them they will be likely to give you an account the second year. First year is tough in all aspects.