Magic Nullification
You can nullify enemy magic by leaving the area map. This will waste the enemy spell, keep doing this until he/she has no more spells left. Example: Mr. Bad cast a magic missile spell, you can get hit or go inside that Inn. If you go inside the Inn, his spell will be nullified. Keep doing this until he waste all his spells.
Magic
Magic spells will always hit their target unless the nullification trick is use.
Missiles
Missiles, such as arrows can miss their targets (i.e. 0 damage, no damage at all)
Money
Most of the money your party collects should first go to buying weapons and armor. Later in the game you should invest in buying magic scrolls, wands, special arrows, and magic potions. Do not hold money back for a rainy day.
Wands
Wands are very nice to have. Investing in wands later in the game is very important. Wand of Frost, Wand of Fire, Wand of Master Summoning, and Wand of Heavens should be bought and not sold.
Arrows
It is a very good idea to invest in special arrows (ice, acid, or fire), bolts (ice, acid, or fire), and bullets. Using these items can turn the tide of a major battle in your favor.
Best Spells
Magic Missle, Monster Summoning, Fireball, Lighting Bolts, Bless, Color Spray, Cure Posion (Slow Posion), and Entangle are my most used spells.
Pluse
Plusing is a good idea. Use the space bar every time a spell is cast.
Bless and Protection Spells
Should be cast before any major fight.
Best Weapon
Best weapon for me was Long Sword +2, +3 vs Doppelganger. Jason Lee (my cousin) likes the Flail +1. Don't ask my why.
Magic Weapons
Any weapon with a + number or unique name are considered magical weapons. These weapons kill monster that are immune (i.e slimes) to normal weapon.
Save Game
Save often as well, and use more then one save slot. Try to use 20+ save slots. It's for your own good. Also save before a major fight. This can save you some pain.
Staying Up
Get some sleep dude. Most of my hits come between 12 am to 3 am.
Secondary Weapons
Missile weapon like throwing knife/ax and sling should be a secondary weapon for all fighters. For your bowmen, long sword, two handed sword, and bastard sword should be their secondary weapon.
Quick Keys
Try to get familiar with the quick keys and the use of the quick item slots.
Scripts
There are some built in scripts in the game. The default setting for each character is none. It is a good idea to set the default to none. If you wish to change the script setting, go to your player character screen and select Customize > Script.
One Handed Sword Vs. Two Handed Sword
A two-handed sword is much more powerful than a one-handed sword in terms of damage. A two-handed sword takes twice as long to swing at an enemy than a one-handed sword. A two-handed sword does not allow you to hold a shield, which can be a major drawback.