If you have already decided on the type of business you want to run, and where you wish to locate it, then the main decision you will need to make is whether you should set it up as a limited company or as a sole trader.
This can be extremely important as you can save a considerable amount of money depending on which option you choose. Both have benefits and drawbacks.
Self-employed is of course cheaper to set-up and less costly to manage since the reporting requirements are lesser than in the case of limited companies.
On the other hand, limited companies do limit your liability in the case of a claim against your business, which depending on the type of business could be the only reason you need to opt for this type of structure. Otherwise, a limited company is rather more flexible when there are a number of partners or when the company has other, more complex attributes.