Best advice is to take your time (by which I mean months rather than weeks). Visit several dealers, and if possible several individual luthiers. You will gradually get an idea of the type of guitar you are looking for - modern vs. traditional construction, spruce vs. cedar (don't worry too much about the wood used for the back and sides - just go for something you like the look of!)
One important decision you will need to make is whether you want to buy a guitar off the shelf, or have one commissioned. Buying off the shelf (from a dealer, or a luthier who has a guitar or two in stock) has the advantage that you know exactly what you are getting. If you have a guitar commissioned, you will be able to choose the tonewoods you want, neck dimensions, scale length, extra features (armrest, soundport etc.), but even the best luthiers struggle to make two guitars exactly the same, so there is a small element of risk.
Finally - it can be helpful to take another experienced player with you when you visit dealers/luthiers, who can give a second opinion, and play the guitar for you so that you can hear it "out front".
James Lister, luthier, Sheffield UK