The goal is to leave with 1337 meat which is the max possible. On a high level, it requires being Ruthless, Dickering, seeking your fortune, killing everything you possibly can (including all four bandits and Gary the Goblin), having level 3 Moxie, and opening the locked box in the mine. Any class works.
This is actually fairly easy once you know what to do. This outlines the important choices -- feel free grab all other items and any other XP. It'll be easier to follow if you've been through the prologue one or twice before.
Turn off auto-spend XP. You'll want to spend it on getting Moxie up to level three first.
At the house: Get Dickern' (from mom), and don't forget to free your bird and grab the needle. You are going to seek your fortune. Head to Boring Springs.
Grab the turnip, get "Mostly Scabs", grab the broken board, enter tavern, grab nasty ring, get goblin quest, talk to Horserer. Go downstairs. Grab newspaper, Nurse Whiskey, kill Goblin (sorry, Gary). Turn in Goblin, ask about Susie.
Talk to Sherf for quest, grab mug #1, get 1 free dynamite, trade needle for 1 dynamite, talk to cactus about the shovel, talk to Horserer for quest, ask about injury, and grab 2 needles.
Go to Orehole Mine, get shovel, grab minecart, grab #mug 2, grab minecart 2 (inside).
Call elevator level 3, unlock and grab crowbar, grab plunger and caps (level 1 and 2), set plunger and cap, and detonate.
Go down and grab meat ore minecart, dig for silver, save Dark Horse.
Go to Boneyard, grab mug #3, kill skele 1, kill skele 2, save Ghost Horse and see graves.
Back in Boring Springs, talk to Susie for quest, go to ranch, get varmint knife, kill bullshead, and grab shotgun.
Go to Snake Canyon, grab shiny rock, kill snake 1 + 2, surrender at snake 3. Then kill snake 3, save Crazy Horse.
Go to Orehole Mine, go back down, use 3 dynamite on the box, open the box and get your 1 meat prize.
Go to Fricker Gang Hideout. Shoot the lookout to be Ruthless. Grab crate for mug #4 and meat.
Ask for soap and then drown the bandit. Approach and shoot bandit in the head. Fight. Grab mug #5, grab door, grab crate.
Go back to Boring Springs, exchange soap for lock, get the pocketwatch, shovel all the poop and dig for mug #6. Go to Sherf and turn in quest and give her the lock. Visit Doc Alice, preen and get Goblintongue.
Enter tavern, get Moxie up to level 3, gamble betting crazy (should get 60 meat) and Intimidate/Hornswoggle/Outfox. Turn in all mugs. Talk to Crazy Pete and sell everything you can.
Go to Horserer and turn in the quest and buy your horse. You should be at 1337 with a horse.