I would reccommend, first of all, a solid phalanx of Necron Warriors.
In any points value above 1000pts, you want at least 30 Necron Warriors.
As far as expanding out from that, you have several options. My personal preferences are Destroyers, Immortals (a staple unit in the Necron army), Pariahs, Heavy Destroyers, and Scarab Swarms. I also make occasional use of Flayed Ones if I am feeling whimsically insane and want to waste points, or I'll forego a Necron Lord for the Deceiver, who is the more fun C'tan to use.
I have written an article for Necron Lord equipment and tactics which can be found here
If the link doesn't work (which it didn't when I tested it) try this:http://www.dicetroll.com/forum/DiceTroll/Article_Detail.cfm?id=6522
Also, make SURE that he understands the phase out mechanic. It's complicated sometimes, but he needs to know several things:
-Who has WBB (all Necron Models, which excludes Scarabs, Tomb Spyders, C'tan, Monoliths (
) and Pariahs
-What ignores WBB and removes models without a chance to get it
-When it occurs (at the very beginning of the turn)
-When phase out occurs (which is AFTER WBB checks
-The distance requirements (must be within 6" of a model of the same type, except Necron Lords)
-What happens to a model if it passes the WBB check (imediately joins the nearest unit of the same type)
-How a new model joining that unit affects it (can raise units back above 50%!)
-And, finally, at what point his army phases out (25% of the total # of models with the Necron special rule [rounding up])
Also, he should be aware of some of the Necron's strengths and weaknesses, and general tactical concepts regarding Necrons.
1. They are a short ranged shooty army, which is difficult to pull off without getting caught up in hth. They excel against whordes armies (due to the sheer volume of firepower), but have a tougher time against medium number tough armies, like marines and other Necrons.
2. They win through saturation fire, not picking certain targets with certain guns. Even a basic Necron Warrior, given enough time, can destroy a Land Raider. They key word is time. You don't have nearly enough of it. Since it takes 1 unit in the Necron army so long to kill big, hard targets, saturation fire is key; keep pumping shots into it until its dead. With the exception of C'tan and Heavy Destroyers, the Necrons really don't have any Big Guns to speak of, so this is how they eliminate threats.
3. Expect combat and plan for it. If you are fighting an assault oriented army, expect to be caught in assault. Pick your targets carefully, usually starting with ones that are easy to quickly eliminate, or those that will negate your WBB advantage. If you have multiple units of that type bearing down on you (eeeek!) then generally you want to pick the one that's closes to you. Or, if they are equally as close, try to kill the one you are more likely to finish off before your opponent's turn.
4. Do not be afraid to sacrifice units. You are the king of attrition battles, and turning what were supposed to be quick combats into bloody, 2 turn meat grinders. If you have an assault unit in your face, as long as you aren't dangerously near phase out, don't be afraid to send a unit to delay the enemy, either by marching in their face and rapid firing, or charging, if the situation warrants it. Note that I would be more likely to do this to, say, a Space Marine Tactical squad than a full blown Command squad. I would whittle that mess down a bit more before charging in. Remember the golden rule that assault armies follow; the safest place to be is in combat. If you're fighting IG, and are about to take a battle cannon round, charge into combat, and you're safe (or, a lot safer than you would have been)!