Use of Non-Forest Terrain
PRE-GAME
The first principal of smart terrain play comes when you and your opponent select and set the terrain. Determine terrain by using the chart in the BRB or just decide based on what pieces you have available. When you dice off to place terrain, watch where he places pieces and decide how you might counter his actions.
In some situations, the terrain will be preset. Observe its layout and determine how it might effect deployment and game play.
The second principal of smart terrain play is clarifying with your opponent how each piece of terrain will operate. Discuss which pieces are difficult, very difficult, impassable, fences and fence-like rows, or buildings.
You'll find a discussion of using your Woodland Ambush rule elsewhere, but keep in mind where you think you might put your free woods when you're placing the standard terrain. Remember, you'll place your free tree footprint immediately before deployment which follows terrain setup.
Consider shooting alleys that you'll leave your archers, north-south passageways and diagnoal gaps. Try to predict how your opponent will deploy and behave based on the terrain layout and how you can benefit from that. Keep in mind your basic principals of attacking from multiple directions; one bit of impassable terrain can spoil that for you.
You'll find Terrain on page 16 of the BRB. It never hurts to reread a section of the rulebook, especially a section so critical to the game. Terrain will effect your army's deployment, movement, magic, and shooting.
GENERAL PRINCIPALS
With mobility and speed as a central concept in their unit design, Wood Elves benefit from terrain in several ways. That said, beware the pitfalls of terrain. Whatever you do, don't ignore the lay of the land.
Line of Sight
Terrain limits, blocks, define, and even expands line of sight for your troops. Elevated positions are often advantageous. Glade Guard can deploy in ranks as desired; just remember that being elevated makes your troops equally if not more visible (BRB 8-9).
Gamers often refer to shooting alleys which are usually north-south gaps created by interposing terrain, but don't limit yourself to thinking only in terms of horizontal and vertical axes. There is an inifinitude of diagonals.
Just consider how many archers you're using and how many can reasonably shoot down an alley. Bottlenecking the opponent with terrain often means that you're funneling him into your shooting and maneuvering against him for flank charges as terrain hampers your troops less.
Hills
Any army containing shooters always should consider availing itself of a hill. Since Wood Elves archers can move and shoot without penalty, deploying on the rear edge of a hill and moving forward to gain range and line of sight is a smart move. Also, deploying back like this can keep you out of the enemy's units' lines of sight.
Don't forget to deploy in ranks with Glade Guard. You can fit 20 in the same horizontal space that you could normally fit only 10.
Glade Guard often receive charges. If you're not fleeing a charge but receiving it, then you want to be on the front edge of the hill so that you can claim higher ground for combat resolution and hopefully a rank bonus, too.
On the other hand, don't marry yourself to the idea of a hill. Hills are always tempting--after all, haven't you seen Dwarfs stack cannons, bolt throwers, and Thunderers on hills and tear you to pieces? However, if a hill is in an awkward location, don't feel compelled to put shooters on it.
Instead, place your archers elsewhere and use the hill to perhaps facilitate the movement of combat units.
Terrain and Skirmishers
Multiple Wood Elves skirmishing units can skirt through difficult terrain without penalty while most enemy troops find themselves hindered to 1/2 movement. From ruins to shallow water, Wardancers, Dryads, Scouts, and Waywatchers cross this terrain with ease. They can charge into combat, avoid the enemy, and shoot across it while staying out of the range of the enemy until you're ready to engage them, if at all, in hand-to-hand combat.
Despite the advantage, always maintain a cautious state of mind. Beware enemy cavalry's extended charge range and flyers. Sometimes your troops will find it best to stay an extra inch or two back from the difficult terrain.
Needless to say, beware, too, of enemy skirmishers, ethereal units, and the like. Remember to ask your opponent about special rules, charge ranges, and such. A sporting player won't mind telling you, and it's not unsporting to ask.
Remember that fleeing units and impassable terrain don't get along. If you have an opponent backed against the wall, press the advantage; but if you find your back against the wall, you better put up a stiff resistance else Orion call you home to the great stag hunt in the sky.
Buildings
Before the game started, you should have discussed any buildings on the battlefield. If it's a tall building, hopefully you remembered to lobby for it to have two floors. Buildings provide excellent cover for your shooters.
Any unit inside a building benefits from a stiff penalty to be hit (see BRB 97 for additional rules). Buildings serve as a viable hideout for a Noble, Spellsinger, or any other character on foot for the same reason.
Remember that a unit can't march or reform and enter a building on the same turn. It might be best to stop your archers four inches away from a building and allow your archers to shoot instead of marching to the building, losing a turn of shooting, and not be able to enter the building that turn. Be patient and you can enter the building the next turn and still shoot.
Any shooting unit benefits from a building's position, but an additional advantage is granted Glade Guard who usually lack 360 line of sight. If you successfully lobbied for a two-story building, all ten will be able to shoot in all directions. It's an excellent advantage, especially once enemy units are within short range.
Controlling a building can also mean controlling or contesting a table quarter at the game's end.
Flyers
When you flee with flyers, consider the path they would take. This includes charging because you could lose the combat or be using Warhawk Riders that will fall back. If your flyers flee onto impassable terrain or woods, they're gone for the game, VPs for the enemy.
Otherwise, terrain suits a flyer just fine. Make use of it to marchblock the enemy from around the corner or across the stream, bait charges, and demolish enemy chariots. Don't forget that your flyers can charge over intervening terrain, so your Great Eagle needs only to barely expose himself in order to glimpse an enemy war machine crew.
Terrain and Psychology
Frenzied troops can really be hurt by terrain. A frenzied Chaos or Orc Chariot sustaining damage as it careens through a rocky stream-bed will make your scouts' day.
Scouts
You save the best for last, right? If you've decided to take scouts in your army, make the most of terrain. Marchblocking from the first turn can be a huge advantage. Waywatchers can get incredibly close and even jump war machines early in the game, effectively neutralizing them. If you can deploy inside a building, do so if it's in a good place and it suits your plans. As stated earlier, this is an easy way to claim or contest a table quarter.
Magic
The Rhymers Harp will carry your troops through difficult terrain, which, despite all the praise above, hinders some Wood Elves units. Treekin, Wild Riders, Glade Riders, Glade Guard, and of course Eternal Guard all benefit from the Rhymers Harp on a character, the last being the most common use.
The Hidden Path spell opens up the terrain even more. It essentially makes the target unit ethereal from the moment it is cast until the caster's next magic phase begins. Charging through a building with a sizable unit of Wardancers or Wild Riders should make your opponent wonder why he ignored his mother's advice to always keep a clean pair of Underoos in his glove compartment.