In my experience, every nursing school has different specific criteria for acceptance. Some are based only on GPA, they start at 4.0 and go down the list until the spots are filled. Others, such at the Univ. of Washington program are looking for the "well-rounded" canidate. Their application points are divided into 5 20% sections: gpa, letter of recommendation, resume, hands on health care experience, and volunteer work (I belive those are correct, but not positive). So if your grades are lacking, but you have years of experience in health care and volunteer in your community, you can make up for it.
My best advise is to go to website of each school you wish to apply to, and the acceptance criteria is typically spelled out. If it's not, contact the advisor for that school and ask very specific questions if you aren't able to make it to the general info session that most hold which will usually provide everything you need.
As far as applying, do it to as many schools as possible and as many times as it takes. Some schools will tell you where you are lacking if you aren't accepted, others are not able to do so due to applicant volume. Some general things are to retake a science or pre-req course if you have a low grade and work to keep a high GPA, even if it means taking one less class a quarter. Find a place to get hands on experience that will set you apart from all other applicants. Being memorable is key when there are hundrends of applicants for only 80 or so spots. It's also important to get your letter of recommendation from a nurse who has observed you in a patient care setting. These are typically more powerful as they will be able to speak more directly about your ability to perform well as a nurse. Volunteer work is also key to some schools, and again the more the application reviewer will look and say "wow, that must have been a great experience", the better. I can understand this is difficult with a family, but don't get discouraged if it takes a while. I just read yesterday that over 125,000 qualified
applicants were turned away from nursing programs last year, due to lack of space alone! Most people prepare for at least 2 or 3 years and doing so activly will help ensure you are a stand out candidate.
If you have any other questions, especially regarding the UW program requirements, let me know (post or PM) since that is the one I am most familiar with and I'll answer any questions I can.
Best of luck, I hope this helped!