Many people will say that the old school style of play does not work well in game where characters have skills. According to this line of thought, players tend to limit their thinking to the skills listed on their character sheet and soon tend to substitute making a skill roll for player problem solving. However, character skills do allow players to play characters who are good at things the player is terrible at.
There is, however, a way to use skills that is compatible with the old school style of play. While it is simple in play, it is a bit hard to describe well in words.
Players are never allowed to say "My character makes a skill roll" as a response to a game situation. They have to describe what their character does to solve the problem just as if their were no skills listed on the character's sheet. Once the player describes what his character is doing, the GM calls for a skill roll under the regular skill rules for the game for dice rolled, target numbers, etc.
The results of the skill roll are not determined by the game's standard rules, however. Instead the results are determine by the GM's opinion of the action described and the skill roll. There are basically two situations:
In the first case, the GM feels that the player has a good plan that should likely succeed. Therefore it will succeed regardless of the result of the roll, but how well it succeeds is determined by the skill roll. A failed skill roll is a minimal success, the character succeeds, but just barely. A successful skill roll means the character's plan succeeds without any major hitches. In games that have fumble rolls and critical roll, a fumble means that the plan barely succeeds but there are minor problems or setbacks the players have to deal with while a critical means the plan succeeded with noticeably better results that would normally be expected
In the second case, either the players obviously knows less than his character does about the situation or just comes up with a bad idea that the GM feels is unlikely to work. Therefore the GM lets the skill roll decide the result according to the normal rules of the game in question. A failed roll means the plan fails, while a successful roll means the plan somehow worked after all, but probably not perfectly.
Players who refuse to even try to come up with some type of rational statement about what their character is actually doing but just want to let the skill roll decide automatically fail.
This method of using skills preserves the old school standard of rewarding player skill while allowing players to play characters who are better at some things than they are.