First thing to keep in mind is that every campaign is different and every GM is, too. Some won't care about the realism of carrying enough food around to survive in the wilds for example. As others have said, the various locations you will go to during the campaign will also have different requirements. What this means is that there won't be a single perfect starting set of gear that fits all and you should adapt to your specific circumstances.
With this in mind, here are my suggestions.
First, check class kits in Ultimate Equipment's Adventuring Gear. Simple but effective. Use these as inspiration to make your own starting kit and note how some of the included items could be a requirement or pure flavor depending on your GM's style.
Then, check the categories below for suggestions. This is my (partial) checklist to avoid forgetting the little (and not so little) things.
Magic / Alchemy
Some of these are requirements for specific classes.
- Spell component pouch 5gp, 2lbs
- Every caster should have one unless they have Eschew Material (Sorcerer)
- Holy Symbol, for divine characters requiring a divine focus to cast some spells
- Wooden 1gp, 0lbs
- Silver 25gp, 1lbs
- Spellbook 15gp, 3lbs for Wizards and Magus
- Formula Book (APG), for Alchemist
- Backpack 2gp, 2lbs
- Pouch (belt) 1gp, 1/2lbs
- Sack 1sp, 1/2lbs
Only if going to dark places or adventuring at night.
- Candle 1cp 5ft radius
- Torch 1cp, 1lb 20ft+20ft
- Flint & Steel 1gp (to light things up)
- Tindertwig 1gp (to light things up)
- Lamp 1sp, 1lb (needs oil) 15ft+15ft
- Lamp, waterproof (UE)
- Sunrod 2gp, 1lbs 30ft+30ft
- Lantern (needs oil)
- Hooded 7gp, 2lbs 30ft+30ft
- Bullseye 12gp, 3lbs 60ft+60ft, cone
Only needed in the wilds or for long travels.
- Ration (trail, per day) 5sp, 1lb
- Waterskin (filled) 1gp, 4lbs
- Feed (per day), for herbivores 5cp, 10lbs
- Meat eaters can consume rations instead
- Herbivores can also eat grass
- The Survival skill can also help
- Mess Kit (UE) 2sp, 1lb (cutlery)
Only needed in the wilds or for long travels
- Bedroll 1sp, 5lbs
- Hammock (UE) 1sp, 3lbs
- Blanket 5sp, 3lbs (recommended with the bedroll)
- Tent, small (Core/APG) 10gp, 20lbs (one medium creature)
- The small tent in APG replaces the one in Core
Tools of the trade
- Artisan's Tools 5gp, 5lbs (required for given Craft)
- Thieves' Tools 30gp, 1lbs (required for Disable Device)
- Musical Instrument 5gp, 3lbs (required for Perform /w instrument)
- Disguise Kit 50gp, 8lbs (bonus)
- Alchemist's Kit (APG) / Alchemy Crafting Kit (UE) 25gp, 5lbs
Some of these depend on expected threats. If you know you're going through poisonous-monsters-filled jungles, you may want to pool money for an Antitoxin or a Leeching Kit.
- Bloodblock (APG) 25gp (to heal wounds/bleed)
- Healer's Kit 50gp, 1lb (required for Heal, +2 bonus when used)
- Leeching Kit (APG) 5gp, 5lbs (for poison)
- Antiplague (APG/UE)
- Antitoxin (Core/UE) 50gp
Miscellaneous Adventure Gear
- Rope (hemp) 1gp, 10lbs
- Rope (silk) 10gp, 5lbs
- Crowbar 2gp, 5lbs
- Mirror 10gp, 1/2lbs
- Shovel/Spade 2gp, 8lbs
- Whetstone 2cp, 1lb (no mechanical effect)
- Bear Bag : bag + 20ft rope, holds inventory (food) out of wild animals' reach
- Bell Net
- Compass (APG)
Alchemy and substances
Apart from the oil, this is very optional, especially considering the costs.
If you are going to travel a lot on long distances, you might want to buy a riding animal, or see if you can rent one when you're starting out. Prices below are for buying.
Basic Light Horse : Horse (75) + Riding Saddle (10) + Saddlebags (4) = 89gp
Writings / Scrolls
- Ink 8gp
- Inkpen 1sp
- Parchment sheet 2sp
- Paper sheet 4sp
- Case for maps/scrolls 1gp, 1/2lbs
- Journal (UE) 10gp, 1lb
- Scroll Case (APG)
- Scroll Box (UE)
- Map Maker's Kit (APG)