Decking out characters
Items that I like to give my heroes asap
2) Metal Shield
3) Hetal Helmet
4) Ring of Mobility
2) Wooden Shield/Metal Helmet
3) Ring of Mobility
5) Wooden Shield/Metal Helmet (the other one)
1) Wand of Healing (Keep wand of fire unless you really need the gold)
Your fighter and archer are you weapons, your mage is your shield. If you keep your fighter out of water and it's back protected, it shouldn't take much damage once it's armour is on. Rush it towards any enemy you see and slaughter them (but keep out of water).
Your archer is good because it is long range, water is an archer's friend because it can stand on one side of a river and pick off all the enemies with special attacks (recomended with shortbow) or normal attacks (recomended with longbow) Your enemy will then have to decide to rush you (if it can) or run (if it can) monsters will not run, if they can't rush you they'll stand there untill you've killed them. If they rush you they'll take water penalty and should therefore be easier to hit and won't be able to harm you (with the exception of bats, who are weak enough to kill anyways).
Your mage is there to heal your other 2 heroes. quick attacks are nearly useless for a mage, always get close to your fighter/archer and use a normal or special attack. a good normal attack should heal 1 hp, special 2hp. If your mage gets attacked by a betle or a rat it'll be able to win, switch to fire wand and eliminate the foe, if it's a bat or a skeliton it's usually advisable to run and get the archer or fighter to kill the monster. Before your acher/fighter get thier armour they are likely to take some substantial damage, so a wand of healing is usually the first item I buy from the store.
The deal with water:
Fighter: stay away from water as much as possible, if a group of monsters (or players) you want to kill can only be got at from water, get your archer to create space, or buy a potion of levitation to clear a landing.
Archer: water is your friend, see above.
Mage: Water is annoying, but seeing as the mage is probably not going to attack/be attacked, it's just the 8ap movement cost that's a problem.
In PvP matches, keep your heroes close togeather, if you get into any real combat with another player, numbers matter more than equipment (in most cases)
In PvE you can spread out a bit more, to find and kill more monsters, but stay close enough so the mage can go between your fighter/archer as healing is nessesary.