There just 3 good options pala sorc ore barb. The slowest but most save one is the barb. With good Items he is fast too but you have too find them first :). The Sorc ist the Master of Teleport but have the lowest Live of them all and you cant kill immunes. With good items you can make Hell Andariel and with a lot of care Mephisto in Hell. I think the most People will say Paladin is the best option in Single ore as a Starter. High Damage and you can kill enythink just with bad items.

The best way too stay alive is too know what attack and Auras the Enemy can have and how too handle it. The Problem is, you can play as good as possible but lag will kill you in the false Moment in the false area. Play with Barb and Bo every time and in a good Party.
What ever you do you cant have the Chance too stay alive on 100% how ever you play and that makes Hardcore sometimes Hard.