How do I start a bar catering business?

First figure out if you want a sole proprietor, parternship, or corporation. Then write out a business plan, try to get a loan or some kind of financial assistance for your business. Wishing you the best on your business.

Sell liquor? You'll need a liquor license (and most places will not let you sell out of a truck - but of course you will need some form of truck/van to haul the stuff around). You'll need cash - no one is going to provide 100% of start-up costs. You'll need food handler licenses, health department permits, business permits, etc. And finally, what experience do you have in the catering industry - do you have a degree in the culinary arts, have you been a chef somewhere, etc. Think about this from the client's end - why would they hire you if you have no experience - they certainly don't want to hire someone where if something goes wrong, they look like idiots in front of their clients, and certainly a bride is not going to want their caterer to make their day a complete travesty (I certainly wouldn't hire you unless you could show me a string of references or a few years working for someone doing catering). Start by writing up a business plan (if you can't do this, you have a ways to go). That will provide your roadmap on how to become a success.