Just made my first necro, whats the best build for pvm soloing hell?

Corpse Explosion

I like:
20 RS
20 SM
20 CE
20 Golem mastery
1-10 Amp
1-10 Revive
1 each decrep, summon resist, iron golem

Level of Amp and revive depends on +skills gear

I like this build because it gives you a nearly unkillable iron golem, allowing you to use nice Insight bases on him while freeing your merc up to wield Infinity. The conviction helps your minions hit (I think) and boosts CE damage by lowering fire res. That plus amp really makes CE potent.

Poison and Bone Spells
Teeth - 1
Bone armor - 1
Corpse explosion - 20

Summoning Spells
Sekeleton master - 20
Raise skeleton - 20
Clay golem - 1
Golem mastery - 1
Raise skeletal mage - 1 (they are too weak one point it is enough)
Blood golem - 1
Summon resist - 1
Iron golem - 1
Revive - 1 (+all skills from gear gives u bigger army)

Curses
Amplify Damage - 1 (manin curse - work great with CE)
Dim vision - 1 (I use thsi sometimes for blinding enemies)
Weaken - 1
Iron maniden - 1
Terror - 1 (good for crowd control)
Life tap - 1 (great for mercenary)
Decrepify - 1 (I only use this against act bosses)

Extra points I invest in bone wall and bone prison. Both gives +15 Damage absorbed from attacks to your bone armor. It is great if you teleport a lot.