Other things to keep in mind: decide beforehand just how much you're ready to spend on a folder. Could be $20 or $200, but be realistic in your expectations and never buy junk, you'll only regret it later. Look for a quality steel. Stainless is the most practical for EDC. 440C or 12C27 is ok, AUS-8, CPM-S30V, 154CM, VG-10 is better. This assumes that the steel is heat treated correctly (shouldn't be a problem with any reputable brand) and hardened to at least 57HRc. Blade shape depends on what you're going to use your knife for (drop point is the best choice overall for an all-purpose knife, clip point makes a sharper tip). The lock should be absolutely secure, strong enough but still reasonably easy to operate. Lockback or liner lock doesn't really matter but if the latter, make sure the knife has solid enough grip scales that the liner lock won't disengage accidentally.

Depending on your daily habits, figure out how you're going to carry it. In the pocket, belt sheath etc. Would you prefer a pocket clip or not? If yes, does the knife come with an adjustable clip that allows a particular configuration that you're most comfortable with (tip up, tip down, left/right handed)? Most better folders these days can be opened with one hand. Thumb hole or stud is up to you. The handle should be checkered, grooved or otherwise shaped to allow a firm grip. Lastly, though a beefy folder is potentially stronger and more durable make sure it isn't too bulky for you in EDC. Good luck!