The first Tower is very easy. You can practice learning the various attacks. Just dont forget that you have to equip your armor (clothes) and your weapon (cryspear). If you dont equip your spear you obviously cant destroy the monsters. The nice thing about the Cryspear is if you take some damage, the Cryspear will slowely replenish your HP. That way you dont have to use up your SBulbs or leave the tower, go to Crysta, and then sleep to replenish your HP. If you've suffered a lot of damage, you can just stand in one place for a bit while the Cryspear heals you.
Once you enter the Tower, the first level is just a large cordoor. There are little purple monsters that look like pill-bugs wandering around, which you can usually kill in 1 hit. They only have about 4HP each. There is another monster now that is a firey wheel that will shoot smaller fireballs at 90 degree angles (very easy to avoid). The fire monster only had 6HP
The second floor is also very easy. Just go around destroying the purple pill-bugs. When the last bug is destroyed, a glowing spirit will appear, give you some advice, and the open the gate to the next floor. The stairs to go up are directly to the right of the stairs that take you back to the first floor.
The third floor becomes just a bit more challenging. There are some of those purple pill-bug monsters again, but now there is another new monster, a large stone-like guard. The guard is big and slow, but he has around 22HP, and Ark's Cryspear only does between 1 and 4Hp of damage at a time. So it does take a little longer to destroy the 2 guards. Once you defeat all the enemies, a little glowing spirit will appear and give you some tips.
The fourth floor has the same 3 types of monsters. When you first enter the fourth floor, dont forget to go down the staircase that will be a little north and to your right. There will be a guard to destroy but you can pick up the MagiRock.