One of the most troublesome parts of knitting a project with a lot of stripes is having to weave in the ends of each stripe when you're done.
But if your stripes are relatively narrow -- less than a couple of inches or so -- you can save yourself some of the weaving by carrying the unused yarn up the side of the work as you knit with the other color.
This requires you to have a project where you're always changing colors on the same side so that you don't have to move the yarn (and thus cut it) during the project. It's also best used when you're going to be seaming a project or if a project is knit in the round, so the carry won't be seen, but you can certainly use it on projects where it will be visible as well (as I did with the Striped Mistake Rib Scarf, which is pictured here.
All you have to do to carry the non-working yarn up the side of the knitting is to twist the two yarns together each time you get back to where the non-working yarn is (usually the beginning of a right-side row).
When you need to start working with the previous color again, simply drop the yarn you'd been working with and pick up the strand you've been carrying up the side. Make sure you don't pull the yarn too tightly or leave it too loose as you weave up the side; you're trying to make it as unobtrusive as possible.
If you're able to carry your non-working yarns up the side of the project the whole way, you'll have a lot fewer ends to weave in than you would have if you'd cut the yarn each time you changed colors. It saves a bit of yarn, too, because you don't need all those 6-inch tails.