Stats = 8/6/17/10

I have just reached level 3, and haven't spent my points yet. My character is supposed to be a thief, but I'm unsure how to effectively play without smashing my head on a keyboard.

The first difficult fight I've had is against the Gemstone Cave giant blue spider, who I didn't beat after a dozen tries. I've seen videos where she's killed in about 6 hits -- well -- I hit her over a dozen in my best attempt, and promptly perished thereafter.

I mean, if I cant beat this sack of venom, how am I supposed to beat some of the insanely difficult melee NPCs I supposedly wont be able to avoid?

Do I raise stealth to max? Does that mean I'm always stealthed? Because there aren't that many places to utilize backstab at my level of stealth (which is 35) right now, at least against the toughest enemies.

Do I raise strength, or just dex? What about const? Or Int?

Do I raise close combat? Or just stealth/technical/object knowledge? I'm not going projectile.

I would appreciate any advice!