Usually a parent's best guideline is to provide a steady, supportive home base while recognizing that there will be ups and downs in students needs and expectations. Try to follow the leads of the students and encourage them to work through a problem with you acting as the coach or cheerleader. Help them balance their thoughts and emotions to make their best decisions. Let them know that you respect their right to make a decision and that you will serve as an advisor when asked. Most parents have a high investment in their student's decisions.
Problems arise, however, when parents are more invested than students.
It can be hard to lessen involvement in a student's decisions out of fear that the student won't assume responsibility. The irony is that students often don't step up to the task of being responsible until parents step back. Taking a step back as a parent is uncomfortable, and at times frightening, because there is no guarantee that students will assume responsibility nor that they will make the same decision as you would. The fear that the student is not accepting responsibility in the interim makes most parents lose a lot of sleep. College is different than I thought it would be.