Skills are are descriptions of the knowledge and talents of a character. They can be diverse as inborn traits and lessons learned on the fly. Skills open the door to information, actions, and options. Skills are not meant as attack options; if they are, they are defended against as a level check plus the relevant stat, such as in Feint.
d20 SRD has thirty six skills, yet the average character is allowed four. In order for a group to cover a wider area of skills, I've lowered the list to twenty-one. All skills are had at three levels; Untrained, in which you have half your level as experience or the relevant stat; Competent, in which you have have your level plus a +3 bonus and the relevant stat; and Trained, in which you have half the bonus of Competent and the relevant stat. (Which, yes, means that at first level Untrained is +0; Competent is +4 +stat; and Trained is +2 +stat, and at second level Untrained is +1, Competent is +5 +stat, and Trained is +2 +stat.)
Skills are gained through race: some races are naturally proficient or teach these skills to youngsters; class: Every class come with a number of suggested skills and the time to train them; and from feats - abilities gained through progression. [d20 conversion to pips: For class skills, take skill Points per level times two; and for Feats, you may gain two pips per feat expended.]
It costs nothing to be Untrained in a skill; although some are Restricted by class, those classes automatically have them at Untrained. Some require selecting a field before you have them, like Local Language or Craft. It costs two pips •• to have something at Competent and one pip • for Trained. You automatically gain Knowledge Local at Trained • in your native land. Lastly, some skills come in pairs, you can choose one skill for one pip, or both for two pips. You can always opt not to select an option, if that's your wish (but isn't recommended).
Simplified Skill List
* - Restricted