To me X is just a way to get a better resolution and a better way to manage my terminals. In fact on 4 virtual desktops the only GUI application is a browser whenever elinks doesn't do the job, everything else is just terminals. Given that it's quite important to get as much as possible out of it, and there are a few things that quite help.

Font

The most important thing whenever you deal with lots of text, and that's surely the case of working in console, it to have a good font, which at least means a fixed width one. Personally I use Terminus but your call really, as long as it's monospace. And dont be tricked to make your font too small trying to fit more stuff in a screen, it seems useful but it's bad for your eyes.

Colours

Use colours to distinguish things. Without ending up with some horrible mix-up, colours can help a lot, for example coloured prompts to identify different machines, terminals, users. I have different colours for different classes of machines, so I know when I'm on a database server, on a webserver, and so on, and with lots of machines this is as simple as valuable. Also it's quite useful to be able to tell at a glance if you're root or some normal user.

Xterm

This is my ~/.Xresources:

spike in space ~ > cat .Xresources 
XTerm*metaSendsEscape: true
XTerm*cursorColor: yellow
XTerm*eightBitInput: false
XTerm*eightBitControl: false
XTerm*eightBitOutput: true
XTerm*saveLines: 1000
XTerm*font:  -*-terminus-*-*-*-*-*-*-*-*-*-*-*-*
XTerm*foreground: white
XTerm*background: black
XTerm*charClass: 33:48,37:48,45-47:48,38:48,58:48

Colours settings aside, the useful bits are the eithBit* and the charClass. Former an explanation of both you can refer to man xterm, bit former will solve annoying problems like Alt-[0-9] not working in irssi; latter will take care of select regions when you double click with the mouse on things like URLs, selecting the whole thing rather than up to the first dot or slash.