You need a lot of motivation as well. It'll take so much more time and effort than you think (at least that's what I find). There's so many small things you don't even think of that take a long time to sort out. Goals are good to keep you working.

There's a balance between cost and buying bolt ons. If you try make everything it'll be cheaper but take forever to finish. If you can afford it buy as any pre-made (pre thought out) parts as you can. I also think it's worth paying people to do the bits you don't like (helps with the motivation).

Most of all good luck and enjoy it!