Realm of Chaos has a tutorial on basing using techniques I gleaned from back in the 1980s when I first started playing Warhammer Fantasy.
basing
Advice on Basing Your Figures
Legio Wargames has a tutorial on basing your figures with wood filler, sand and other bits.
Using Children’s Board Books For Bases
Here’s an interesting idea about using an old children’s board book as a base for making terrain. I think there’s lots of other uses for this readily available source of thick cardboard.
Making Desert Bases
Big Lee’s Miniature Adventure has an article comparing various methods for making desert bases for 6mm figures. The techniques, of course, can be applied to any scale.