ok, all I can advise on is vs Necron, as 'crons are my primary army, and I have yet to face CSM. That being said...
The most common 'cron army at 1k will have 1 Lord, 20+ warriors, and either destroyers, immortals, scarab swarms, with the possibility of wraiths, tomb spyders, and heavy destroyers. Don't worry about pariahs, monoliths, or c'tan, as they are simply to pricey for 'crons to take at 1k.
First thing first, focus on one unit at a time. Assuming the Lord has a res. orb, the necrons will get WBB against nearly every attack, unless you wipe out the squad completely and there is no similar model within 6". If you spread your fire out, having lootas shoot at one unit, deffkoptas at another, and charging a third, then all your efforts will be in vain.
Secondly, prepare for highly mobile units. The lord, assuming equiped with Veil of Darkness, will be able to remove the unit it is connected to from the board and deepstrike it where ever the player chooses, meaning you will likely receive rapid-fire gauss in the back the turn after you hit his lines. The destroyers move like jetbikes, and are more than powerful enough to deal with just about anything in your army.
Thirdly, hug terrain as much as possible. Destroyers have a 36" range, warriors & immortals 24", and those shots will hurt. I play against tyranids, and when he doesn't hug cover, by the time he gets into combat with me, there are only 8-9 gaunts left of 4 full squads.
Finally, the warriors need to be your primary targets, followed by Immortals, then the lord and destroyers. The warriors are going to be his primary source of necron bodies, and if you take those out, it will only take a bit more casualties to force a phase out. (If a necron army falls below 25%, after WBB, of it's original number of "true" necron models, the necrons automatically lose). Don't overexpose yourself in an attempt to kill them, but they should remain your goal.
There are two strategies I can see working. One is to claim more, distant objectives then your necron opponent, forcing him to spread out and advance. The warriors need to remain in a tight clump around the lord for maximum phase-out protection, and if you force him to advance, you can hopefully isolate and overwhelm one unit at a time. The other option is to ignore objectives, hug terrain, and take the fight to him ASAP. Necrons are terrible at CC, so if you manage to reach him w/o taking to many casualties, you should be able to take out most of his army in a round or two of assault.
Good luck in your game.
edit- added paragraphs for my own sanity - gutstikk
