What courses do most colleges look for in applicants?
They are looking for people with good personalities.
Generally, the courses that they want are:
4 years of English
3 years of Math
2 or 3 years of Social Studies
2-3 years of Science
A foreign language
This is a very general list. Different colleges have different standards. You should check any specific college's requirements.
In addition to having the right amounts of each type, it is also helpful to have the harder classes on the transcript versus the easier ones. For example, you might have the right amount of math classes, but the college won't like it as much if you took Pre-Algebra, Algebra 1, and Geometry versus Algebra 1, Geometry, and Algebra 2. The higher you went up on the track the better because that shows you are ready for harder classes. Sometimes, you can even take Advanced Placement or Pre-AP classes. Advanced Placement classes are supposed to be the equivalent of a college class and can even count for college credit, if you play your cards right. The point is, don't just get the right amount of classes. Try to have some of the classes be the challenging ones.
One thing that might help you is to go over what their minimum requirement is. If they want 2 science credits, it might look better if you took 2.5 or 3. That will show that you are more prepared than people who simply took the minimum. It will also make you more prepared for college level coursework.