ok. I can tell you how i play. I have 48 Necron Warriors. 1 Necron Lord. One Monolith, 4 Wraiths, 4 immortals and quite alot of Sacrabs. 6 flayed ones. Ok, this is quite alot of Points. But you have to work it out. It depends on how big army you are going to play.
Monolith - You can only have two Necron Squads out in play from the beginning. The other two groups is in the monolith. You can get them out later in the game.
Scarabs - Move slowly forward with you'r Necrons squads, leaded by the scarabs. Playing this way, makes it impossible to charge you'r Warriors. Scarabs, 3 wounds, really irretating to kill
Flayed Ones - CHARGE! Ripp the skinn of you'r oponents.
Wraiths - Extreamly powerfull in Close combat. Moving 12", really fast.
Necron Lord - Keep this in the middle of one of you'r Necron Squads. When you'r Warriors gets hit, they fall on their back, and thanks to the Necron Lord, they rebuild them selfe by getting 4+.
Immortals - Maby one of the most powerfull Anti-tank units in 40k. REally great.
Optional: Night Bringer - Extreamly powerfull. 5 wounds, 5 atacks. 24" weapon. I blew up a tank on one shot. Really fun, Cloud Runner got quite angry, but i had to get my friends revenge, cause in the first turn, cloudrunner blew up the Ork tank. Dammet, first turn! And the tank costed 190 points. What a loss really
Anyway, i hope this could be any help
Tell me if there is something else you were wondering.