Kristy, it sounds like you and I are on a similar path in this portraiture thing. I am going to run through some things I learnt from my first couple of shoots (which were only recent). Some, or all, of this may be stuff you already know, but getting the right thought process is my main learning point and I thought I'd share in case it helps.
Pre-shoot
If you aren't already, think about how you want the light to fall on your subject. Do you want her face evenly lit, broad lit or short lit? Does she have a "good" side. Once you know how you want the light to fall on her face, you know which direction she'll be facing.
Given your knowledge of the location, think about what backgrounds you can use, given the orientation of your subject. Think about how that same light will fall on the background and whether it will complement the subject or distract from her. Are you getting a reflector? Do you need a reflector to make her "pop" a little from the background?
I imagine you've photographed your sister before. What camera level looks best? Above nose level or below? Or either? Do you need to bring a step to stand on?
Get some inspiration from Flickr, Pinterest, 500px or the like. Make a list/diagram of basic poses to fall back on. Maybe even give your sis a "heads-up" on the planned poses???
On the day
Set up your tripod early. Even if you shoot hand held the whole time, don't risk the chance of missing some shots at the end of the fading light while you set up your tripod.
As you move through the various locations it might be good to have a planned routine/checklist for quickly setting up. My first couple of shoots have, at some point, wound up with me getting flustered.
It looks like you are going to take a white balance shot for each locale. This might be good as before you take the white balance card shot, you'll have to check you are getting a good exposure at each new set of lighting conditions. I won't comment on how you arrive at the "artistically correct" exposure in the shortest amount of time. Keep bumping up your ISO to give yourself a fast enough shutter speed.
Once you have your exposure and white balance card shot sorted, check your model top to bottom. Hair still in place? Make-up? Clothing sitting nicely? (Is anyone else there to help with this? A second set of eyes helps a lot with this. It would've helped me anyway)
Take lots of photos, but don't get flustered like me. Every photo needs to be focused on the closest eye, otherwise you are possibly just taking another frame for the recycle bin. Consciously think what you want included in the frame. ie. is this a head and shoulders or half body shot? Am I including the hands or cropping them out? What am I including in the background?
With the rapidly changing light, you'll be tempted to rush and miss focus or forget about composition. Don't.
Talk to and encourage your model. I'm sure the talking part comes naturally to most sisters. The encouragement is sometimes overlooked between some
. I found it helps to show a couple of early "keepers" on the back of the camera to build their confidence. Your confidence, (or lack-of), will reflect on them too.
Others have commented on posing, another thing I am trying to learn.
I would possibly forget flash for reasons Manfred states. It may put a catchlight in your model's eyes which might be nice. However, if you use aperture priority, using flash may force you to use a certain shutter speed. I think my D3000 defaults to 1/60s under some conditions. I'm not sure exactly when or why so I end up in manual mode whenever using flash. Maybe you can set your exposure without flash, then for the last few shots at a spot, pop up the flash and see what happens. It'll also drain your battery faster. Do you have a spare battery? Possibly another reason not to use flash?
Good luck!
Edit: I just worked out you're the Kristy who started the
Lydia thread
You've got a much more comprehensive rundown on thought process from a much better source (William W) in that thread. Hopefully my comparatively amateur musings added something.