I never rode anything but friction shifters until this year. There's nothing to it really, it just becomes a matter of feel, which you get better at with use.

That said, if what you want is a cheap bike for transportation, and would like indexed shifting, go with an older mountain bike from the early 90s. They have indexed shifting, cantilever brakes, bombproof frames, and are dirt cheap because nobody wants them. I've got two of them now-- one a Trek 830 that my landlord gave to me, and the other a GT Karakoram that is almost showroom pristine that I bought for $50. Swap out the knobbies for some commuter slicks, add a rack if it doesn't already have one, and you've got the perfect city bike/commuter...With indexed shifting.