"Scratching the surface"
Everyone who has ever used wally knows about it's predone features. I'm talking about the scratch tool, the bullet tool and the rivet tool. These can be great tools if used properly.

Scratching
Adding scratches to your textures can give them a really nice worn look. Or you can scratch the edges of your textures (or any portion) to give a bevelled look. If you create a nice rock texture but you find it's a little too flat and nice you may use a scratching method. You'd cover the entire texture with scratches (thinest variation). Remember to do it in tiled mode. Once you've completely scratched your texture, you can add a little more noise and then blend it heavily or medium.
You can also use the scratch tool to create cracks in your rock walls. The scratch tool can add light where you don't want it (and dark as well). So it's always to go through your textures with a lighten or darken brush just to keep up the consistency of the scratch / crack.
I was told by shaithis (owner of the Texture Studio) that I went a little nuts with the scratch tool. Sadly thats true =) Try to limit yourself when you use scratching. Doing variations such as scratched and unscratched gets old and doesn't show much effort at all.

Bullet Holes
The bullet hole feature of Wally has to be one of the most unused features. Most people can't find a use for these except...well...bullet holes! I find bullet holes look nicest on a damaged wall. I've seen some people create a nice clean texture and then they just add random bullet holes! Halflife does that for you! Theres not really a need unless you're creating a texture that has obviously been through a war. In this case you'll want to add cracks, bullet holes, stains (rust dark blood) and scorch marks. If you're going to go for the battered texture look don't assume that a couple of bullet holes will do the job.

Rivets
Rivets are cool. Perfect for a narrow beam texture. But as always they can be addictive. Next thing you know you'll be adding rivets to grass!
Rivets can look good in few or mass quantities. They give the texture that 'bumpy' quality. If you're going to use rivets then decide which part of your texture best suits them. Alot of people create 'multi-walls'. Multiwalls is just another name for a texture with either a footer, header or side texture. You'd have a nice generic concrete slab with a metal beam stuck on the side of the texture. That metal beam is the perfect canidate for rivets. Covering the entire beam can look cool but is somewhat unrealistic. Using only four (or less) rivets may not give enough of the effect desired. Try different numbers and spacing parameters with rivets. You'll eventually find the perfect combo! Once you've rivetted that metal bar, it'd be a good idea to make it seem higher than the concrete. You can use scratches for a quick but small height change, or you can use the darken tool and take it from darkest to least.
Nothing here is really that specific. More like theory =) I'll be doing a specific hand drawn texture tutorial very soon. Thanks for reading and happy texturing!