Talk to someone else who contracts and get advice on what a sensible day rate is. Then simply contact recruiters and say you are a contractor and are looking for a contract.

I got into it by mistake when I applied for a short term position without even being aware of the concept of contracting. Turns out getting contracts is typically easier than getting a full time position as there’s less risk on the part of the employer. They can just get rid of you if you turn out not to be good.