Fallout 3 skills

Skills in Fallout 3 are a primary attribute of the player character that determines their effectiveness in a variety of situations.

History
As in the previous games, the player chooses three Tag Skills out of 13 to be the character's specialties. However, unlike previous games, tagging only rewards the player an extra 15 initial points to that skill. Five skills have been cut out from the game (Fallout and Fallout 2 had 18 skills).

Formula
Initial Values (Fallout 3): [(Stat + 1) * 2] + Luck Bonus. (ex. Starting STR of 5, starting LUCK of 1 will give you an unarmed skill of 13 base. [(5 + 1) * 2] + 1 = 13). Initial values also function as base value, meaning any later change to the SPECIAL stat would also have similar change to the respective skill.

At level up, the character will gain 10 plus their initial intelligence level. Again, increases to intelligence after you leave the vault initially (when you have your last chance to make character changes) will not impact your skill points at level up, so plan accordingly. (i.e. Skill points at level = 10 + INT). For example, With intelligence of 5, you gain 15 skill points (10 + 5). With an intelligence of 5, plus a intelligence bobble head and a Intense Training perk for a total of 7, you still only gain 15 skill points.

Improving and Maximizing Skills
Skills can be improved...
 * temporarily...
 * by wearing equipment with modifiers
 * by using chems
 * permanently...
 * by 1 or 2 points by reading books depending on if one has the Comprehension perk
 * by 10 points by finding the corresponding Bobblehead

Note that it isn't possible to raise a skill above one hundred points. With all the ways listed above of raising your skills it is not advisable to put 100 points into a skill by means of leveling.

Glitches/Explotable Bugs
It is possible to never have to put points into certain skills to max them out. In particular, certain skill books are on respawning NPCs - merely waiting 72 hours after killing will result in a new copy being created.
 * Big Guns - U.S. Army: 30 Handy Flamethrower Recipes skillbook on a respawning Raider with a Flamer in Bethesda Offices East
 * Science - Big Book of Science skillbook on a respawning Ant Researcher in Shalebridge Tunnels (friendly ant colony side)