well in apem or sdem you start with about 600 gold, so i usually max out bear/natural attunement first, and start ganking people at level 5 (level 3 bear) hoping for a lucky entangle. (you don't need wild to gank because your bears base move speed is pretty high and with boots i think its about 400)
my first items:
on bear: loggers hatcher + buckler
on hero: health potion
pretty much jungle right away, let your bear tank
eventually your bear is going to need to heal, but by this point the cooldown is usually up so i let my bear die the first time and then recast and keep jungling
the second time he needs to heal the cooldown is still going usually for me, so i send him back to fountain and i tank the creeps (which is why i have the health pot), not forgetting to transfer the buckler + loggers hatchet to my hero for the time being
then at level 5, your ally is probably soloing in your lane against 2 heroes, so you can go behind them and coordinate a gank (but first when your bear goes to heal grab both of yourselves a pair of boots, and your hero a agility shield (+6 agil, 100% to block 20 dmg by hero).. and if you can afford it gloves of haste

steamboots on your bear
keep jungling, and level up wild, i usually don't get bear form until around level 10
the items i eventually get are:
bear: buckler (helm of black legion if the enemy heroes are targetting your bear) + treads + thunderclaw

charged hammer
wild: 2 bracers + agility shield + ghost marchers (if the enemy heroes are targetting you, so you can run away while your bear blocks them while constantly spamming your bears blink to block/entangle them while you run)/steamboots (if they arent going for your hero), thunderclaw if you guys are owning/frostburn if you need the extra movespeed + health (you will get 522 movespeed on your hero/bear with wild + ghost marchers)
usually by this time my game ends.. but if it hasn't i usually get warpcleft on my bear and eventually daemonic shield
you should generally be untouchable if your micro is decent and you ward your forest to prevent ganks
*** a lot of people like radiance on the bear, but honestly i don't think it's necessary, but hey if you farm up enough gold for it then go for it
also i generally don't use bear form much because you have lower movespeed and you can deal lots more damage in range form
also.. if your team doesn't have much disable/stun, basher on your bear is kind of cute
/inb4tl;dr
EDIT:
apparently a new patch, just made wildsoul a lot better!
Wildsoul
- Damage when the bear dies now properly goes through immunities
- Updated his tooltip to reflect that he takes damage when his bear dies
- Beardulon abilities reworked very slightly
* Gains Return at level 1
* Gains Entangling Claws at level 2* Gains Demolish at level 3
* Gains Magic Resist at level 4
- Wild cast time removed, letting him cast it on the run
- Base movespeed while in Bear form increased from 270 to 285GFG buffs, the cast timer on wild was really annoying when you were chasing/running away, and bear form is much more useful with the move speed buff, and entangling claws at level 2 means you can go for a level 3 gank if necessary
This post was edited by BB_MelloYello on Jun 11 2010 10:39am