For me, one of the downsides of carrying a pocket knife is keeping it in your pocket, where you want it. Aker Leather has an inside-the-pocket holster for pocket knives designed like the tried-and-true pocket holster for small handguns.
The holster fills the bottom of the pocket, and keeps the knife (or handgun) in a fixed position. The rough-out leather provides a bit of "grip" to keep the holster from moving, with the slick side of the leather on the inside to provide a quicker draw. It also disguises the shape of the object, to help avoid "print through". You always know where your knife is, for a smooth deployment.
Rather than jam the knife all the way to the bottom of the holster, I just hook the pocket clip onto the top edge. Then I can draw it with a thumb on the top of the holster, pushing down, while the index finger pushes up on edge of the pocket clip. This results in a point-down carry, which isn't my favorite, but I can live with it.
Incidentally, my new "carry" knife is the assisted-open (legal equivalent to a switchblade, but better) Kershaw Cyclone. It has the interesting feature of a slide switch on the back that turns the AO feature off or on. In the "off" position, it works just like an ordinary lockback. Here it is, compared to our standard Camillus 904S:
Opened, here are the two knives again:
The holster costs $30 (just a couple bucks if you can make your own leather goods), and seems to me to be a reasonable investment for someone who takes carrying a knife or a weapon seriesly. People who are serious about their carry permits will often spend hundreds of dollars on concealment holsters for various occasions.
For me, this is a good investment for a $100 knife ($49 on sale).