There are hundreds of different sites explaining step by step how to set up a Twitter account. None better than here at Twitter headquarters (Of course!)
Before set up I would like to emphasise the following:
Twitter username/handle: make sure you choose a name that explains either who you are or what you are about.
Profile: you only have 160 characters to explain yourself. Make best possible use of them. If you are an artist then include the word artist. People searching artist will then find you.
Picture: it has been statistically proven that Twitter users who post a picture of themselves on their Twitter account have an easier time finding followers. It’s sort of like a dating game you know!
Make yourself easy to follow: there is an option allowing you to vet tweeters before they are allowed to become your followers. Do not check this option. You can always block tweeple later if their contribution is deemed unsavoury or (worse) just plain boring.
Here’s that set up link again: Twitter set up