Running a business has nothing to do with it being your main source of income. I've been DJing for years and been running it as a business all that time but it's never been my main source of income. One of the first things I did was register a business name. That way I could use that name on any advertising and especially my Yellow Pages ad (which was extremely effective back then, not so now) and not worry about anyone else using it. Imagine if you spent hundreds of dollars on Yellow Pages and as soon at it came out someone else registered the name and you were no longer legally allowed to use it! Insurance - most people only think if it when they need it and by then it's too late. You may be able to cover the loss of equipment under your contents insurance (make sure that you can) but no matter how carefully you set up your gear, you cannot 100% defend yourself from someone injuring themselves and sueing you. Me, I'm rather attached to my house and all that I own, so is it really worth the risk? As mentioned before, some venues will not let you in the door without proof that you have public liability cover (and it's not that expensive). Licences - it seems the attitude is that if I can't get caught then I don't mind breaking the law. Playing music publicly and without a licence is breaching copyright law. Pure and simple. No matter how you justify not paying the licence fee (ie I know for a FACT that NONE of the money reaches the artist). So is it ok to run your business illegally? I guess that's up to the individual. Back-up Equipment - Tough call if you are on a limited budget, but again you will find for the true professionals this isn't an issue and is always on hand. With reference to one of the other posts, it's not about making sure your gear is reliable and hiring some for the next gig if it breaks down. It's about what do you do when you're playing at someone's wedding reception on the other side of town and half way through the night your amp or your controller dies? Do you have a back-up amp or a spare CD player and enough CDs to get you through the gig? Just things to consider if you plan on running a successful (and legal) DJ business.