No issues at all, it's so much fun to do whatever you feel like doing!
There are only three attractions with single rider lines (Test Track, Expedition Everest, and Rock N Roller Coaster) -- be sure to take advantage of those.
Will you be using your FP+ during your solo touring, or will you wait until your sister joins you later in the day? If you are using them, after you use the first three, you can sometimes get decent fourth and subsequent ones, since you are only looking for one person.
I'm a big fan of some of the shows (Festival of the Lion King, Finding Nemo, Frozen Singalong -- don't judge, it's hilarious, Beauty and the Beast). Don't miss those!
Have a blast! I usually tour solo, and I enjoy it every time.