It also depends on what style of play you'd prefer, and if you're into painting models, if you want few models to paint, models easy to paint, etc. If you don't like painting, be prepared to pay someone else to do it, or you might get stuck with not touching your army for months or years.
There's also the advice from
>>3083219and it's quite good. Seriously, check the races/codexes, see what you like.
There are some "general tactics" for each race which have been pretty much the same since they were created, even if there are other ways to play them, for example:
* Tyranids are a close combat army and usually have swarms of small creatures, as shields, lesser dangers, etc. They're generally bad at shooting. Be prepared to use terrain, deep strike or move forward very quickly. Tyranids, if you play them right, never worry about morale, ever.
* Tau focus on shooting people up before they get to the Tau. They die in CC. Moving out of the way and firing is their general tactic.
* Imperial Guard have swarms of kind of weak troops, and are a bit better at shooting than CC. People have traditionally liked Imperial Guard for the swarm troop tactics and their tanks. Very much their tanks. They've always had a fine selection of tanks. The only real shame is that there's mostly two kinds of IG troops out there sold by GW - Catachan(rambo people) and Cadians. FW has Deathkorp, but they're friggin' expensive. If you're creative though, finding neat humans isn't all that hard.
And so on. These will give varying amounts of help, of course. Incidentally, I play Tyranids. I should really repaint them so I can play some again.
