Map knowledge is very important. Especially in something like Factory, you should know where all the player spawns are (there are 6). Factory is also usually recommended for new players just so they learn the gunplay and basic mechanics.
Hatchet runs at first to learn the maps, try to kill a scav for a gun (or look around, guns with ammo do spawn in some places), then when you start feeling more confident about your map knowledge start bringing guns so you learn the gunplay.
A good way to make money is to bring a pistol into Factory and kill people who only have hatchets. Getting one dog tag from a decently leveled player can be worth like 30-40k, which should cover at least a few pistols or one AKS. Or what most hatchet runners do, spawn and rush straight for the office safe and stuff your safe container full of whatever's in the safe. Lucrative and boring, but can get you money for some gun runs.
Also try Factory runs in offline mode (you won't lose (or gain) any gear) with PvE enabled to get a feel for your guns and pointshooting ("hipfire").
SKS is a great gun, use PS ammo (HP does tons of flesh damage but is shit at penetrating armor), and if you get some solid hits you can take down anyone. SMGs are pretty shit at the moment (next patch in a week or so will introduce Mp7 with AP ammo though), the ammo can't pierce good armor, but they do kill really fast if you aim for the legs. Same for shotguns, shit armor penetration but kill fast if you hit flesh targets. AKS (remember to crouch when firing full auto) and SKS should be your go-to guns until you can get AK74Ns and AKMs etc.
Here's one pretty action-packed Customs run from beginning to end (with some shit cut out of course, real raid lasted 18 minutes)
Also, DON'T start Skier's first task until you've found a fort armor and a kiver helmet. It's timed.
Keybinds that aren't mentioned in controls:
https://gist.github.com/TheDonDope/8327101ead7758b9bfc6e86b9a776f80Change sprinting to hold like the above link says, feels much more precise that way.
