Pixel dungeon is about good position when fighting enemies and correct use of the limited resources.
Try to identifie as soon as possible all potions and scrolls, try them out in a closed chamber on top of water in case you junk down a flame potion.
Save your upgrade scrolls for better equipment, if by floor level 7-8 you havent gotten a better armor than leather then spend some of them on your armor.
As a gladiator you favour fast weapons (mace and fist) if you get one early spend your upgrade scrolls only on that weapon.
Always focus with your scrolls it is better to have a bit inferior weapon tier with more upgrades than a higher tier weapons withouth upgrades.
try to fight in narrow passages and behind doors so you only face 1 enemy at once and you get the bonus acuracy and damage from first hit from behind door.
As a warrior treasure the food you find, it is better to get to the starve condition get some damage and then eat the food it will heal you some hp.
if you have a heavier amor that you cant use because of strenght requeriment, if there is a fight you can change into it and let the enemy come, if you dont move you dont consume extra stamina.
try to be always at the same level than the floor you are in.
you can farm potions with bats and flies, unequip your weapon and try to hit the flies in a open space
have your drew drop vial always maxed out in case of emergency.
can't think of more tips
For more info oficial wiki: http://pixeldungeon.wikia.com/wiki/Main_Page