Played fallout 3 - did not find it as hard as this game, I spent 5 minutes in prim trying to sneak attack 2 convicts... they slaughtered me, with pistols.
Many seasoned pro's and semi-seasoned are probably scoffing at this as an act of superiority, nevertheless - I seek advice.

Before I go to Prim, is there any good places or side quests I can do that can help a low level guy like me become a bit better against handling myself in the great world of fallout... or at least deal with a few convicts.

well you might want to think about lowering the difficulty level at first then after awhile once your set with stimpacks and enough ammo for a good weapon increase the difficulty.

New Vegas is a lot tougher in FO3, but its a good thing. Early on, grab as much dynamite as you can off the powder gangers. They aren't hard to kill. Dynamite is a good early weapon to have. What are you wearing for armor?

I've never had a problem killing these 2 convicts at level 2 on Very hard. What I do is use the regular varmint rifle and see if I can buy the scope from Chet in Goodsprings. Also, if I find (or buy) other varmint rifles I just repair them. I go around towards the NCR tent on the other side of the road from Primm and pick up those frag mines.

Sneak towards a building or somewhere I can hide.
Place frag mines on the path towards your hiding spot.
Sneak attack with a headshot.
I've killed them both with a single headshot each. (on VH)

Or you can go in guns blazing and spam some stimpacks.

I find shooting them helps. Early in the game I think that enemies are weak enough that you shouldn't need to sneak attack, just get close and shoot. Enter VATS if you want. Spiked knuckles will also kill everything early on with ease.

was about to suggest this