It's hard to say how many schools to apply to. I am applying to 6-7 schools. I know others who apply to many more, and some who even applied to much less. It gets expensive to apply to a lot of schools, so that's something to keep in mind.
A lot of the schools I've noticed say that they look at the complete package (GRE scores, GPA, CV/Resume, Experience, Volunteer work, Personal Statement, Letters of Recommendation, etc) rather than one component. From what I've gathered through looking on SOPHAS, the schools individual websites, and from the forums here, you should definitely write an awesome personal statement/statement of purpose, and you should make sure that you look at each school, as some of them have different requirements. Some schools require work experience, others don't. All the schools are different. I have all of the information in a notebook and that way when I apply, I have a checklist for each school of what I need to make sure I have so that I do not send an incomplete application. That's all I can think of right now. Hope it helps!