I havn't hit the max level yet, but if you need a few pointers I can help you out.
Plan out your characters stats as to what you wanna do, because when you get invaded or invade and play with blue phantoms, they need to be within 10 levels of you to play, although it ramps up as you get higher, 25 levels when your around 100, etc.
After beating 1-1, if your looking for a solid weapon right off, there is a crescent falchion +1 in 4-1 on a cliff guarded by a black skeleton. You can also trade items to the crow alittle futher in for rings, souls and arrows. Finally if you can get scurry past the Vanguard, you can find an uchigatana also.
The guy in 3-2 that starts killing everyone ( I think his name is Yurt), the best option is to immediately kill him after freeing him, you can just backstab and kick him off the ledge, then reload your game and all his armor will be on the ground outside the cage he was in.
The magic spells you wanna obtain if your going as a heavy mage would be Fire spray, Firestorm, Homing Soul arrow, Warding, Cloak, and Soul Ray.
Fire spray becomes crazy when magic hits 70+ and you use the Kris, Ring of magical sharpness, Monk heads collar, or Clever Rat's Ring and the Morion Blade. You can use the spell while sprinting and it only takes up 1 spell slot.
Homing Soul Arrow ROCKS, it only takes 2 slots, and it is pretty much 5 soul arrows that hover around you and fire when an enemy comes near, I can easily do 1500+ damage with a single volley from this.
Kinda jumping around here, but good weapons to get are Moon/Blessed/Crescent anything, Dragon Bone Sword, Meat Cleaver, Blueblood Sword, Lava Bow (even if you don't use bows), and the purple flame shield. The katanas in this game are kinda limited unless you upgrade an uchigatana, but the makoto is good if you can offset the health drain.
Sorry for being all over the place, Havn't posted on any forums in awhile.
Great website for information : http://demonssouls.wikidot.com/