Raise Your Attributes As High as Possible When Leveling
Every time your character gains a level, you will get the opportunity to enhance three of your character's core attributes (strength, intelligence, willpower, agility, speed, endurance, personality and luck). The number of points an attribute will be raised varies from one to five depending upon how many skill points your character has gained in skills governed by that attribute, in accordance with the following chart:

I’ll have some of that. Purchase skill points from trainers in order to increase your attributes quicker when you gain experience levels.

For the purposes of determining the attribute multiplier, all skill points gained through: (i) using the skill; (ii) reading skill-enhancing books, or (iii) purchasing skill points from trainers, subject to the qualification described below, all count towards determining the number of skill points gained during the level. There's one qualification to that general rule applicable to the X-box version of the game and the initial PC version 1.0 release. In that version of the game, skill points purchased from trainers for miscellaneous skills (i.e. skills that are not your character's major or minor skills) do not count towards the total number of skill points gained for the purpose of determining the attribute multiplier. In other words, in the current PC version of the game, all skill points gained through any means count toward determining the attribute multiplier, while in the Xbox version all skill points gained count other than points gained through purchasing training for miscellaneous skills.

You'll be able to develop a much more powerful character if you ensure that you bump the attribute multipliers up prior to gaining a level. Even if you've raised your minor and major skills more than ten points, you won't gain a level until your character has an uninterrupted rest, so you can control the timing of the level gain. As soon as you rest and gain a single level, the attribute multiplier is reset to zero. Through training, it's possible to accumulate enough skill points in your major and minor skills that you'll be able to repeatedly gain several experience levels by resting, but it's unwise to do so. If you rest again immediately, you'll gain another experience level, but you'll only be able to raise your attributes by a single point. Instead of immediately resting, you should always first try to gain additional skill points in order to increase your attribute multipliers again.

Players of the PC version of the game have a key advantage because of the distinction noted above. Since skill points gained through purchasing training for miscellaneous skills do count towards the attribute multiplier in the current PC version, you should use any available funds to purchase skill points in miscellaneous skills prior to leveling. By doing so, you can ensure that you can increase your attributes by up to 5 points each, which will allow you to quickly create a very powerful character.