Do your homework, know what characteristics you want in your cue. What kind of hit, taper, balance point, tip diameter etc. The best thing you can do is to hit several cues from the same maker and do this for as many makers as possible. Each cue and even shaft will have a nuanced hit, but you can get a feel for those makers who's cues give you the feedback and action you're looking for with your stroke.
Draw up some plans for your design particularly if you're wanting something that is non standard. Make up your mind about what woods you want in your cue, what kind of inlays etc. Determine how thick you like the butt of the cue. If possible go to a big event with lots of cuemakers like the Super Billiards Expo and try out as many cues as you can. You might just find one you like there out of the thousands for sale.
Once you're narrowed your choices down to 2 or 3 cuemakers, call them up or talk to them in person show them your drawings, discuss what your preferences are and "LISTEN" to what they tell you. Some may not want to build the cue with YOUR design or they may suggest different woods. Some will not want to build your cue if it is too far removed from the type of work they are doing. Others will love the challenge.
Do your homework, check out the cuemaker, get references, do research and buy with confidence.
Finally, my personal experience has nearly always been dealing directly with the cuemaker as opposed to a dealer or cue flipper. There's different ways to do everything but I've been the happiest when I had a direct relationship with the cuemaker with no middle man.
Good luck in your quest.
Rufus
P.S. You can't stop at just one, or two or 13 or....