Treasure brought back from an adventure will be awarded 1 XP per 1 gp value of coin/currency. This means non-coin treasure will need to be converted to coin to count and any value adjustments might factor into the value (e.g. taxes, haggling).
E.g. 100gp of silver, 1x gem worth 50gp, and 1x painting worth 500gp are recovered. The painting is fenced for 200gp and the gem is kept by the magic-user. The PCs share 100 xp for the silver and 200 xp for the painting.
See Advancement and Awarding XP in the SRD.
Rewards, bounties, and patrons count for XP.
Does not count:
Group XP based on what's been found, not based on what each individual character collected.
Leveling up requires a relatively safe environment
In "town" where it would be reasonable to spend 1-2 days resting (aka downtime), with some exceptions based on plot-timing.