Okay, let my start by saying that I do not consider myself an expert, if you have any ways to improve my guide please post them below, the more information we have the better 
Getting to the God Wars dungeon,
For Bandos you will require 1 item from Zammorak and 1 item from Bandos,
Cheap options include;
Zamorak robes (top or bottom)
Unholy Symbol (Zamorak)
Ancient Mace (Bandos)
Bandos Boots (Bandos)
The best way to get to the god wars dungeon (GWD) is via the Trollhiem teleport spell which is unlocked after the completion of Edgars Ruse Quest, I would also recommend doing Nightmare zone for the redirection scrolls as this will save you an inventory slot when teleporting. after teleporting use the agility shortcuts to the East to descend down to the bottom layer of Trollhiem then run north with protect of missiles on (Ranged) and push past the giant boulder (requires 60 Strength) if this is your first time you will also require a rope, but this is only needed once.
Okay, so first of all we will look at a SOLO trip.
Requirements:
70 strength.
A Hammer - Dropped by the goblins used to get kill count.
40 Kills of the Faction you're trying to enter. (in this case 40 Bandos kills the most commonly used are the Goblins)
Reccomended:
85+ Attack, Strength, Defence as a minimum.
70+ Prayer with Piety unlocked.
Recommended items:
Armour: Barrows or Bandos, a mixture of good ranged & Mage defence is Best (Karils/D'hide top with Good melee legs)
DFS or Crystal shield.
Weapon: Minimum of DDS for specials, whip for regular attacks
Dragon/Crystal Halberd/Godsword and Tentacle Whip preferred.
Optional: A set of Guthan's armour will allow you to stay longer, if you're prepared to risk it.
Inventory: Prayer potions, Teleport Method, Hammer, Fill the rest of your inventory with food Sharks, Saradomin Brews + Super Restores.
Optional: Bones to Peaches Spell & High Alch Runes.
ONLY BRING ITEMS YOU ARE PREPARED TO LOSE. The God Wars dungeon is one of the most dangerous places in RuneScape. Don't take it too lightly.
Reccommended strategy:
To enter the boss room, you must first kill 40 followers of Bandos. I recommend either killing Goblins or Hobgoblins to the west of the entrance. Once you have all 40 kills "Bang" the door and enter the bandos side room (NOT the Boss chamber) Go slightly north and stand outside of the Bandos door.
Make sure you have prayer points, set your Quick Prayer to Protect from Melee & Piety.
Make sure your Auto relatilate is turned off, and you have your attack options set to right click.
Put on Prayer, Drink your Potions, Quickly chage into your armour if needed (only needed if you're wearing Zamorak robes still) and enter the door.
You'll notice your kill count is drained, if you leave you can't re-enter without getting kill count (or using an Ecumentical key)
Attack Graardor and after 2 hits walk under him, this helps prevent him from using his ranged special attack too often.
Graardor has 2 attacks: melee and range. His melee attack can hit 60 (possibly more), and his range attack is strong too. The melee attack, however, is single target, where as the range attack hits ALL players in the room.
During the fight you have 3 concerns:
-Sergeant Steelwill's magic (medium risk)
-General Graardor's Ranged attack (high risk)
-Sergeant Grimspike Ranged attack (Medium risk)
The melee attacks of Graardor and Strongstack are no risk because you have Protect from Melee on.
Once Graardor is dead you can kill the minions one, by one, use prayer to reduce the damage you take and use Guthans to heal if you have it.
It is possible to Pray flick all of the minions but this takes a high level off skill and much practice, I do not recommend trying this unless you are very experienced at PVM.
Now for Duo/Team GWD;
The role of the tank is as described above,
However some slight changes occur if you are the Attacker.
Gear should be maxed Str/DPS i.e full Bandos with Dragon Defender.
Also the Attacker should set his quick Prayers to Protect from Missiles (Ranged) & Piety.
Always allow the Tank to enter the room first, once Graardor has attacked him only then may the attackers enter, after each kill the attackers should stand on the S/W Wall while the Tank stands in the center of the room towards the east, once again only attack Graador after the Tank has.
If Graardor picks you as his melee target, turn on Protect from Melee FAST! Either try to tank as described above or Start running a few steps away and he may switch, then start hitting again. If he hits you hard, EAT! Alternatively, Be careful: you will take damage from his ranged attacks.
As for the minions;
Your hitpoints should always be above 70, otherwise you're in danger of being one-hit by a combo.
Steelwill will switch targets alot, hitting as many people as he can with his magic attacks. If he targets you, watch your hitpoints and keep them above 70. He should switch targets after a few hits.
As for Strongstack (melee) and Grimspike (range), they pose little threat. Strongstack might hit you fairly high (50+), but as he uses melee it's easy to run and eat. As for Grimspike, he's harmless since you're praying range protect.
You can use the altar once every 10 minutes, so use your prayer wisely. If you run out, you're done for. If you only use Protect from Missiles and your team is quick at killing Graardor you should manage through 10 minutes and still have prayer left.
If you have a set of Guthan's, use it to heal on the sergeants once Graardor is dead.
Hope this helps please post improvements below.
