Turntables can be difficult because even if you audition at a dealership it’s hard to separate what the turntable is doing from the rest of the system. But that’s probably the best most people can do. I do a lot of research, and read reviews. Not for the subjective opinions because there are so many conflicts that are undisclosed for magazines and reviewers that I don’t care about their subjective opinions. Plus, they are listening in a different room with different equipment from mine so even if it’s an honest review I’m not sure how valuable it would be. On the other hand, you can learn a lot about the features of the table, construction quality, etc.
if you can go to a show, it’s great to actually see the products and a demonstration. That’s not always feasible but very helpful if you can do it. I agree with @ghdprentice that at least for me, I would always buy my turntable from a dealer. Arm and cartridge matching can be tricky. Also, set up can make a huge difference with a turntable. A lot of people can get them to play music, but if you get your table set up by a real pro I think that makes a tremendous difference.
Good luck!

