I'm not sure. Some of the skills in Fallout, like Science and Speech, don't really lend themselves to being practiced all that well. To make the system work, the functions of those skills would have to be drastically expanded, which would actually be pretty great regardless of the leveling system in place, or they'd have to be merged with some other skills, which is an idea I'm not fond of because it cuts down on skill customization. I don't think I want to see the Fallout system changed all that much, though; both series' systems are valid and have their own perks and drawbacks that make each one distinct. I wouldn't mind seeing Skyrim's ability to save perk choices for later added to the Fallouts, so you're never in a position where you're forced to take a perk don't want. While we're at it, maybe even add the ability to save skill points for later, which would be great for giving new players a chance to figure out which skills they like using before they have to make any choices about where to put their points.
Anyway, Fallout: New Vegas already has the special perks that you can only get by performing specific actions, like the "Bug Stomper" perk that you get for killing mutated insects. Maybe just add more perks like those? It would add some element of the Elder Scrolls system, the beauty of which is the fact that you get better certain things by actually practicing them, without getting in the way of what's already in place.