With how the board is set up, it may be geared toward the eldar players (lots of cover and LOS blocking objects). IG do well when they can bring all their guns to bear on numerous targets and cause widespread damage, this will be difficult to do with a dense terrain type board. Eldar (both types) do well when they are able to isolate enemy units and wipe them without much fear of retalitory fire, this makes dense LOS terrain ideal.
My suggestion, dig in and force them to come to you. Try to find a good spot with open space around a bit of cover. On top of a structure/terrain piece would be ideal for your troops. This would make the approach difficult and assaulting very risky (difficult terrain tests are the bane of many assault oriented armies). Without any cover to run through, any infantry would be fish in a barrel. This is where your heavy troop weapons come in (Lost of fire from atop difficult/cover saving terrain). To force them your way (if they aren't already rushing headlong toward your line) take some barrage weapons (the IG has plenty of these). Make them hurt every turn they try to hide or reposition themselves. Focus these barrage attacks on troops by capture points. If you cna make them run/die, that is one less point the enemy has. If assault troops are getting to close, focus them with your infantry/heavy weapons. Avoid using large template weapons that close to your line as they will inevitably scatter onto your own troops. Once they lose the ability to assault, your sheer weight of guns will win the day. You may also want to take a goodly supply of grenade launchers. These are fairly cheap and can be fired as blast helping to cope with poor IG BS as well as having a chance of breaking DE vehicles.
Having played both against and as eldar/deldar, flamers eat them alive. Heavy flamers are especially good at this as they break armor, ignore cover, and easily wound the squishy space elves. Chimera's are your friend here. Heavy flamers with grenade/plasma/flamer troops inside will allow you not only to wipe any cover-hugging infantry from the board but also to rush forward on the 4th-5th turn and grab/contest a couple capture points.
That said, watch out for warp-spiders, jetbikes, wytches, and Harlequins. All of these (and some unnamed others) can close the distance quickly and take out key targets (such as your company's order barker or specific heavy weapon teams). The spiders and jetbikes can move attack and move again preventing most retaliatory shots. The wytches will make short work of anything IG in melee and when jumping out of an open topped vehicle can assault turn 1 over a distance measured in feet. The Harlequins effectively ignore difficult terrain and can have perma night-fighting rules about them in addition to being very able melee fighters. This allows them to move through flanks you thought were secure by terrain.
The last key point is eldar/deldar need to commit wholly in order to accomplish anything worthwhile. These armies cannot pot-shot and "kill the odd unit" to attain victory like the IG. Because of this, taking a full platoon in reserves can help; especially when they are destroying what you had on the board and are in a state of disarray. (A friend of mine uses this strategy against me regularly and with good success. I commit my army, wipe his from the board with some casualties, and then must recuperate from the attack when the other 1/2 of his army suddenly appears in what is now an ideal (for him) and completely compromising (for me) location and arrangement).