By Shonono of Koguryo:
The most difficult thing about being a warrior for myself was the need to buy expensive weapons and armour, and also find good food such as bear livers for emergency healing. I spent a lot of time in the Rat caves from level 15 or so and sold Ginseng in Hamgyoung-Namdo and Topaz from Centipedes to other players. I also killed alot of squirrels for acorns!
When I could use the flank spell, I began to gather wool and sell it to weavers. Flank attacks make it easy to hunt Sheep. Now at level 32, I began weaving myself!
Around level 36 I began hunting in the Iron Labinryth. The bears were dangerous but because they dropped a lot of livers, I could find enough food to keep going.
There are many warrior spells that require fox furs. So I spent alot of time in those caves. I think the Kugnae has more Sun Foxes than the Buya fox caves.
After I passed level 40 I began hunting in the Mythical Rabbits. They drop amber and provide alot of experience.
I found the Chung Ryong Dojang website had very useful information for training young warriors. The advice about where to hunt for lower level warriors was especially helpful! Be sure to also read The No-Nonsense Guide to Leveling as a pre-99 Warrior.