A good miniatures paint job can be ruined by bad basing; on the other hand, a miniature with an average paint job can really be enhanced by an inspired base. Here’s some advice on making scenic bases for your miniatures.
Matt Fritz has some advice on printing and basing paper soldiers for your miniatures wargames.
Star Ranger has this advice for basing your starship models. There are lessons to be learned here for players of Battlefleet Gothic, Full Thrust, Star Fleet battles, and other science fiction miniature wargames.
Realm of Chaos has a tutorial on basing using techniques I gleaned from back in the 1980s when I first started playing Warhammer Fantasy.
Legio Wargames has a tutorial on basing your figures with wood filler, sand and other bits.