Half Skills (4e Variant Rule)

Half Skills
I wasn't a big fan of the 4e skill system where a skill is either trained or untrained and that is it. I am, however, a fan of the way skill checks scale with level and the training system is a small bonus tacked on top of level and ability score.

Here is a modest modification to the skill system that should be able to be easily incorporated into any game.

Skills have 3 ranks of training: untrained, trained, and mastered. For every trained skill you would have got with the basic rules, you instead get 2 training points (so a feat that gives you an additional trained skill will give you 2 training points, a class that gives you 3 trained skills give you 6 training points, etc.). Each point can raise your rank of training in a skill you are able to train.

Untrained skills give no bonus. Trained skills give you a +3 bonus to checks with that skill (and count as trained for all purposes if it ever comes up). Mastered skills give you a +5 bonus to checks with that skill.

This shouldn't drastically change a game, besides allowing players to have a bit more granularity in picking what they are good at and what they are really good at.

Some Other Ideas to Consider
You could split the training into 6 ranks (including untrained). Each rank would give a +1 bonus, to a maximum of +5. This would allow very granular training and be something akin to an actual skill point system.

If you want skills to be earned during play, you could actually reduce the number of skill points the character starts with and award them at certain level breakpoints.

If you don't really think it would be overpowered to give out free skill points. Just give out a skill point at a level up if the character has been making good use of that skill. For example, if the party has been doing a lot of diplomacy, it wouldn't be horrible to give them a free skill point in diplomacy when they level up. Just don't do this too often, or else the players that actually invest in these skills might feel a little short-changed because they are not gaining bonuses to a skill they have already mastered, but their fellow PCs are.

Spending 2 skill points to learn cross-class could be viable. I would make it cost 2 just for the initial training and then cost 1:1 thereafter. That way with the original variant I suggested, you would spend 3 points to master a cross-class skill, leaving a point open to train a class skill.