I’m with Len – having a good music library is probably the most important thing to have when contemplating starting out as a DJ. You can get away with not having the top brand equipment, as long as it is reliable. However, you will struggle if you don’t have the music.
I often get people that want to come out on a show to learn and most make the same mistake and want to play
what they like to listen to. You need to be more flexible than this – be prepared to play
stuff that you may personally hate. If you are offering your services to a client, then you need to be playing what they or their guest want to hear. A good aim is to keep the dance floor
working. If you can do that then you are doing ok.
Take requests and be polite when that one person is requesting something inappropriate. This all gets noticed and will go a long way in defining you as a professional. I hear lots of horror stories from clients and a lot relate to the DJ being rude, arrogant or just plain lazy.
A lot of it is knowing your music and what will fit where and how to step it up or take it down as required.