Also, I always put a cb (circut breaker 150A at min) or fuse in the power cable.... install it as close to the terminal as possible. That way if the power cable manages to earth itself it won't burn your car down.
I normally run the power cable through split loom or conduit, then secure it with rubber lined P clamps. Obviusly keep the cable away from sharp edges, tight radius changes, heat sources, and any other chafe points.
In the engine bay, make sure your positive connection has a cover on it... There are lots of great power distribution blocks etc that can be found in marine catalogs.
There are some reasonably good kits in truck/4wd stores that include a box ( a must for a wet cell battery) terminal clamps, mounting plate/brackets, cb, cable etc.
Make sure the earth cable is at least the same size as the power cable.
If I don't run a full length earth cable, I usually run the earth cable from the battery to a solid/structural part of the chassis, then in the engine bay I'll usually earth everything to one point on the same structural/chassis part. eg on a 4wd I'll earth the batt to a chassis rail and earth the engine etc to the same chassis rail in the engine bay.
Lastly, it might be worth getting an auto elec to look over it once your done. Just to be safe.
Cheers
Justin