Some scholarships are based on merit. You receive them by meeting or exceeding a certain requirements. Merit based scholarship can be given on the basis of academic achievement or a mix of academics and a special achievement, trait or interest. Some are given based on financial need. There are also other scholarships targeted on selected groups of people, such as women’s or graduate students or based on meeting a certain background criteria. Therefore, you will need to prepare additional evidences depending on what you apply for. Be sure to check the requirements stated on the scholarship site.
You can usually apply to universities after you have received your scholarship. However, it will usually help your scholarship application if you have received conditional offer letter from universities. If you fail to receive offer letter after a certain deadline from your targeted universities, some scholarships program will cancel your scholarship. As this depends on the scholarship program you apply for, be sure to re-check the scholarship details.
During the selection process, you can usually apply to several scholarships program. However, most scholarships will be revoked if you accept more than one scholarships program.