My #1 piece of advice: you NEED a balanced college list.
What that means is that you have a healthy mix of colleges that qualify as likelies, targets, and reaches.
How many colleges you apply to is going to depend on factors such as region and major, but a good baseline is to create a list that is 40% likelies, 40% targets, and 20% reaches. That means if you are applying to 10 colleges, you should have 4 likelies, 4 targets, and 2 reaches.
Likely schools (also called safety schools) are colleges where you have an 80%+ chance of admission. Your academic profile exceeds the average student admitted to this university.
Target schools are colleges where you have 20-80% chance of admission. Your academic profile matches the average student admitted to this university.
Reach schools are colleges where you have <20% chance of admission. The average admit’s academic profile exceeds yours, or the college overall accepts less than 20% of applicants.
HERE'S WHERE IT GETS TRICKY: This past admissions cycle was so competitive that many college's admissions rates went down. A school that may previously have been a target for a student became a reach, and likelies became targets.
To help you build a balanced list, I offer a service called College Match. You tell me your preferences around colleges and what schools you're currently considering, and I make a balanced list of likely, target and reach schools for you to explore. I take into account this past year's admissions results as well as other individual factors that can affect admission, like your major or hometown.
Purchase College Match here!