Necros are not that bad if you know what you are doing. Here's my quickie newb necro advice:
I would get your strength up to at least 60 to wear decent armor/shields. 75 is better. Much more is overkill unless you find something spectacular that requires more than 75.
Leave dex at base.
Vitality should get the bulk of your points in the end, with a lot in Energy as well. For a while, try and split points maybe 3/2 between the two, more into energy if you drain your mana ball too fast. Then pump Vitality as much as possible.
Put at least one point into every curse. They all have their uses (except Weaken, but it is a prereq). Most of them don't need more than that unless you use them a lot and would prefer to have a higher radius/duration. Dim Vision is great for early levels, it gets less useful later though.
I don't use the skeleton side of the summoning tree, it is not strong enough and can cause lag for other players. Stick to the golems. I like Fire Golem myself. Throughout Normal level, you can use the Clay/Blood Golem + Iron Maiden combo, it works wonders.
The poison skills are pretty weak IMO. Poison Nova is OK but don't waste points elsewhere unless you are going for a melee build. You can pump Corpse Explosion early on, it is entertaining and pretty effective. Try and eventually put at least 10 points in it. Later on, Bone Spirit is going to be your best direct damage spell. Bone Spear can hit multiple targets but Spirit does more damage.
Oh, and put some points in Bone Armor, very useful spell.
And be SURE to hire an Act II mercenary. I like the "combat" merc, he uses the Paladin's Prayer aura which regenerates hp for himself, you, and your minions.
OK, I've babbled long enough.
