I have over the years have pondered around with level editing and doing the stuff with JED, but I tend to really put little thought into what textures I should use. I have always used a colormap other than the drab 'difl.cmp' and I have made the mistake of not getting the textures to work. I basically need a little bit of advice to try to make my texturing more intresting and get it to reflect architecture and dynamics. Okay, Okay I want to get to the next stage of editing and try to improve it, but I need a bit of a hand.

If you've got any ideas, discuss

There are only two ways: either you collect a massive amount of premade textures and have some clever naming, so you can actually find a fitting one in a respectable timeframe, or you start drawing your own.
And please, use 16-bit textures.

I actually like to use JKEdit for texturing purposes. Its interface makes it really easy to see your level. Also, it's finally freeware. A handy feature in it is click on a texture you want, press CTRL-C to copy its position and CTRL-V on an adjacent one to copy it and positioning. Therefore you don't need to line up every single face to the next one.

Granted, JED probably has a feature like this but 1) I'm ignorant to it and 2) I stuck to jkedit for this cause it works nicely

in JED 3D preview:
Click textured surface, press (;)
click adjacent, untextured surface, press (')

Last two paragraphs in the basics.