Copywriting projects start with a clear brief; often developed together with the client (objectivity at this stage can be invaluable). I'll want to understand your goals and the market context. I may also need to liaise with the designer, animator, film-maker or anyone else involved in creating the final product.
I normally provide a fixed cost for each project, based on a day rate plus out-of-pocket expenses. We'll agree this before I start.
If it's a big job I'll draft the structure and key messages and discuss these with you before I write any copy.
You'll then see a first draft, often in the context of the design/layout or as a storyboard if it's for a film or animation.
I think it's important to see the draft copy 'in situ' as close to the final product as possible – it's surprising what a difference it makes.
There are bound to be revisions and further drafts before copy is finalised (hopefully not too many!). You will need to proofread and take responsibility for any copy before production of the finished item, just as you would with any artwork.