Skills are related to your attributes. If you have a dexterity of 8, you'll see a (-1) bonus that goes to everything related to agility. Defense will suffer, ranged weapons, stealth skills will all suffer by 1 point. If you improve dexterity to 14, you'll get a (+2) bonus for everything related to dexterity.
Wisdom and charisma are related to the number of force points you get per level in the first game. Charisma has little influence in the second game, mind you. A higher intelligence provides bonuses to computer skill, repair, and security.
You can eliminate all the penalties you get by setting all your stats at 10. When you create the character, push your favorite attributes to 14, but don't go any higher, as it costs more of your original stat points. Your bonuses all go up by one for every two stat point you improve.
One other thing: if you use Force valor, you improve all your stats by 2 points. That essentially raises all your skills by an additional point.