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(a) What would you suggest to improve my GPA (besides getting better grades)?
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That's like asking...How can I improve my salary without making more money?.
You need to study, study, study to bring up your grades. With a 3.4 junior year, you can't bring it up high enough for ivies. Many schools don't use senior year grades to determine admission.
However, if you bring your grades up this year, many colleges will like seeing that "upward trend" of rising grades.
You will still have plenty of good school choices....so don't think you have no hope...
What is your financial situation...that, more than grades, can limit your choices at this point.