One terrain system I've seen is a purely randomized one:
1. Roll a D3 and add 2, this is the number of pieces of terrain to place.
2. Place a Deviation template in the center of the table.
3. For each piece of terrain:
1. Roll a D6 and consult the following chart:
3. Water feature
4. Linear Obstacle
6. Rough Terrain (Or Trench, etc... depending on what you have).
2. Roll D6, this is the direction
3. Roll 2D6, multiply by 2. This is distance.
4. Roll D6, this is orientation (starting orientation is based on how it sits in the box).
5. Place the terrain piece as described by the three rolls above. If you have different color dice, you can roll the previous three roll all at once.
It sounds complicated, but it's actually pretty quick and easy. It does tend to leave the terrain in a rough circle around the center, but that's generally reasonable. If you want a more random setup, change the roll in Step 3 to 1D6 but multiply by 4. If you roll exactly the same direction and distance for two different pieces of terrain, reroll the second, otherwise overlaps are fine. There can be a little fudging if a linear obstacle pokes into an obstruction or something too.
One suggestion: If playing with a scenario try to avoid any major pieces of terrain in any scenario zone (obstructions mostly). Small obstructions, linear obstacles, hills, and small forests are alright though, as long as there is only one per zone though. If this happens, just reroll the location of the offending piece of terrain. The rules say not to place terrain in deployment zones, but it's rarely a problem for me.