I'm a current student at UK. Maybe I can help. Any questions, just ask.
As for testing, like the ACT/SAT, it's useful to find a good book, or even some prep classes. Sometimes the high school has teachers or after school stuff who will help. Mine didn't but, I heard other students had teachers who took time to practice. Simply googling ACT practice, or info about the ACT will help a ton. And remember, a good ACT will help a below average gpa. I got a very high ACT, my gpa was barely above average, but a lot of colleges would love that ACT score. Only problem is that the gpa might hold you back when you want to get into certain programs or scholarships. I don't know much about the SAT. I never took it. I applied to UK in November of my senior year. Got accepted around the end of year. I had considered Vandy, UL, and UT a bit. But I grew up around campus, and felt that UK had good enough programs to get my bachelors from and if I wanted to pursue further I could look around for the best specific university for my needs.
Im my experience, its best to go out and look for scholarships, than to expect them to come to you. There are tons of stuff out there. There are definitely going to be the standard university scholarships for gpa and etc, but lots of money is out there for stuff you wouldn't expect. A quick google search will reveal it.
I never officially visited anywhere. I've been on campus at UK more times than I can count. I had visited UL with a friend who went there. I knew people who attended Vandy and UT. I got their opinions on the school. I'm sure an official visit would be nice, but for me it wasn't a huge. issue. I would have been happy with a crappy campus if the programs were ok. If she's living on campus, then I would visit. Try to visit when you think it'll be nice too.
Key for application stuff and admissions is just get them done in timely fashion. If you're applying for multiple schools around, there is something called a Common Application, which makes sure you don't have to have to make an individual application for each school. Apply early, make sure you study on all applicable programs (like honors, etc). If you're getting FAFSA stuff, then do it early. I believe the window is different for each state, but at least in KY it opens early in the year and last for a long time until the middle of the year. Other states might have smaller windows.
As for application itself, just make sure you think of everything possible to make yourself look good. Teacher recommendations, clubs, sports, anything and everything. You want to make yourself a well rounded individual on an application. More than likely some applications (for UK at least) might have you write a short essay about something you've experienced, etc. I'm not sure how important it ultimately is, but dont rush through it and take it lightly.
As for college itself, the big thing is just to find a balance where you are comfortable. Learn where to study. If she's living on campus, maybe with a roommate or something, then use the libraries. You never know what might happen in a dorm. Tell her to relax. Lots of first year students get stressed and overwhelm themselves. Its important to have some way to enjoy yourself. I would probably blow up from all the crap I've gone through, if I didn't find a way to vent. Stuff isn't going to go a students way all the time, but you have to be able to stand up for yourself and do your best.
I'd say definitely try to advise her to get to know professors of classes she enjoys. I personally got to know a few, and ended up talking a lot with them outside of class. They can be great role models if its an area you're going into, and very helpful when it comes time for recommendations if you need them. Overall, it's important simply to just be able to get involved in some way. You won't gain anything by never speaking or having a voice. I learned that very quickly in a lot of my classes. It's best to get out of your comfort zone and do stuff.
The only thing I would have done differently in college is not declare my major when I started. I came on with a decent amount of college credit my first year. I declared history, having taken 3 AP History classes in high school and it being something interesting. I'll graduate with a history degree, but I can definitely say that you don't want to find yourself halfway down a path, questioning if you made the right choice. She can take her time and figure it out as she finishes her basics.
That was a lot more than I thought I would write, hope i helped in some small way.