To start best is to make a HtH or a fastshot spammer (requires 5 ST). Get your 3 first levels by mining and crafting shotguns and ammo (that weapon is easy to use with low sg skill). Take adrenaline rush at lvl 3 then go hunt some shit in TB until you beefed up a bit.
Nope.
If you want to start properly, you go with a simple build.
EG:
First you travel to gunrunners and get yourself +10% SG, then you travel to the boneyard for another 150xp for exploration. Head to NCR afterwards, gaining 150xp. Once in NCR you can do busters ciggaretes quest and mira's debt. By now you'll be past lvl 2. Once you leave NCR you can go ahead and do the tent quest, gaining lvl 3.
Once you have done the all above, you'll have a tent (best placed near hub/JT mine) and a weapon. NOW you can go mine some ores for a 10mm pistol and ammo. You should also get yourself a knife (gained from tent quest) and collect fibers from any fiber plant you see around the wasteland.
Fibers can be turned into ropes, which are 100 caps each at the small gun store at the marketplace in the hub. Trade ropes for guns, ammo and caps. Gather enough caps to get SG1, SG2 and Armorer 1 + 2. Also (slowly) gather caps for books.
With good professions, a tent and equipment you can start hunting chests. Blueprints, caps, weapons, armor can be sold or used. Be sure to hunt chests at remote areas (eg waterworks), even consider making a new tent there.
last but not least: Be sure to gather 10k caps and buy yourself a DIY outpost, these come with fiber plants and fruit (for flamer fuel).
There's many ways to level up from the scratch, but this is how I would do it. Consider tagging BG instead of SG, if you dont mind mining a bit more for ammo. M60 is exellent for PVE.