After choosing your specialty and favored attributes, you must assign five skills as Major skills and five skills as Minor skills. These are the skills that will count toward your level increases, so you must give some serious thought to which ones to use. Here are a few things to consider when making your choices.
Assigning skills that you will not use is the best way to hamper your character's development. Yes, it's nice to be able to use any weapons or armor that you can find, but if you've assigned a skill slot to Blunt Weapon and then spend the rest of the game slicing and dicing with your nifty Daedric Wakazashi, you've essentially wasted a slot that could have been put to good use with Short Blade. Decide what you want to be able to do and then stick to it.
In order to gain a level, you must increase any or all of your Major and Minor skills by a total of ten. This means that you can have ten skill increases in one skill and gain a level, or you can have one skill increase in all ten skills and gain a level or you can increase two skills by four and two skills by one, or any other combination you can think of. As long as the total number of Major and Minor skill increases comes out to ten, you get a level increase.
When you gain a level, you also get three tokens that you can assign to particular attributes. Each token increases the attribute to which you assign it by one point. Some attributes, though, will have multipliers. Assigning a token to an attribute with a multiplier, increases the number of points by which the attribute is raised. For example, an attribute with a x3 multiplier will increase by three points. These multipliers go with the attributes whose skills have increased since your last level increase. If you have installed the patch, this includes Miscellaneous skills. If you have not installed the patch, Miscellaneous skills do not count.
The skills you assign to your Majors and Minors increase much more easily than those in Miscellaneous. By assigning Major and Minor skills that cover all attributes, you stand a much better chance of receiving multipliers to all attributes (except Luck, of course), or at least more than one or two.
Here are a few suggestions for types of skills to assign.
That's six out of the ten available slots. The remainder can be whatever other skills fit your character.