Brandon,
I am sure they have a "electrical for dummy's" out there somewhere. You really cannot go wrong putting in the new GFCI's. They are made now so if you wire something backwards, they will not reset. Also, pick yourself up a little outlet tester for a couple of bucks. It is a 3 prong plug that has 3 lights on it. It will tell you if you wired something incorrectly. These things are a must for Sec 8 landlords. Sec 8 requires all 3 prong outlets to be grounded and they test each one with that tester. I spend days pulling 3 prongs outlets and installing 2 prongs on rehabs.
When a GFCI is required, that sucker has to be grounded for Sec 8, the easiest way to accomplish this is to go straight to one of your cold water pipes. Most homes are grounded at the water meter, which will give you a ground on your cold water pipes. When you are installing GFCI's on a second floor bathroom, you certainly don't want to have to try to run a ground all the way back to your box in the basement. If you do not have a ground on your water meter from your box, put one on. It will save you a lot of time.
Several times I have ran into upstairs bathrooms that did not have an outlet. What they do have is two candle stick lights with push button switches and no switch on the wall. They make a GFCI outlet with a light switch built in. These are perfect for installing a new light bar, with a new GFIC outlet and switch right over the sink. Your line is already coming up from the basement to power your candle stick lights, so all you have to do is run a new line up to your light bar from your new switch.
I have installed 3 of these things so far and every time I do, I spend at least 2 hours trying to get the thing to work correctly. Each time I had to call the support line on the box and the guy walked me through the process. I cannot read electrical diagrams for crap, so the instructions were useless. This last one, I saved my notes and hopefully I won't have to call the company again. It is absolutely necessary to wire these correctly or the GFCI or the switch will not work or it won't ground correctly. So you really cannot create a hazardous situation, the outlet won't let you.
Another great source for instructions that has saved me countless hours, is your local Handy Man hardware or whatever small hardware you have in your area. The one I shop at has old timers working there and they are more then willing to sit down and show you exactly how to do something, whether it's electrical, plumbing or painting. I often pay a little more for my supplies at this store, but it beats spending hours trying to find what you need at the big box stores and you are supporting your local community by shopping there.