Sleep in a bed after gaining enough major skill increases
Gain 10 total increases in your major skills to level up
Open the character menu and check for the level-up prompt
Choose which attributes to increase when leveling up
Increase your major skills by using them in gameplay
Train skills with trainers to help reach the next level faster
Use skill books to gain additional skill increases
Level up only after resting in a bed or owned bed
Repeat the process until you reach the desired level