Iirc Ive added an additional 4-5 grounds around the engine bay, and it certainly helped raise my voltage. I also resanded(made sure no paint or rust) all the factory grounds to ensure a solid connection.
The alt is grounded by the block, so I always run a ground wire on the pivot bolt to the chassis to ensure a solid ground.
Kevin has some good suggestions.
This seems to have made small improvements (at least) for a number of people that I've read about doing it, so it's definitely worth a try. Would start with the alternator personally, and go from there. It's definitely one of the more critical items given that your entire electrical system relies on it.
