Start drawing rough ideas of what you would like. In the end you will probably have about 6 drawings with things you like in each. It's then a matter of deciding what you really want/need and what you don't. It took us over a year but it was worth it.
The other thing to consider is finance. We set a ceiling and came in under it as we did some of the work ourselves (painting, floor etc.)

Just take your time so you get what you want.