You don't need a lawyer to file a Delaware certificate of incorporation... it's simple enough to do it online. But even though you are a single-owner, you may need a lawyer to help with:
If the business idea, plan, and present or future value (or liability) are worth protecting to the point of incorporating, then it is probably also worthwhile to develop a relationship with an appropriate attorney. The right relationship with an attorney will prove to be a much more valuable asset to your business than an online incorporation.
(The preceding is not legal advice and does not create an attorney/client relationship between us.)
Yes, you can do it yourself.
However, given that you will be looking for outside funding, at some point - before you talk to prospective investors - you should have a lawyer examine your corporate documents to figure out what will be required to put everything in proper form.
Disclaimer: This information does not constitute legal advice and does not establish an attorney-client relationship.