Ask your reference people for their letters well ahead of time. Be sure you provide all the relevant information with your requests. For example, if you are asking for a reference from an employer, include your full name, the dates that you worked for the company and what your title was. Hopefully the person will remember you, but you want to make this as easy for them as possible. On the same note, if you are requesting a reference from a professor this is even more important.
Professors deal with hundreds of students every quarter.
Make sure you provide them with detailed descriptions of the classes you took with them, when you took them, what grade you received, and any other relevant information. It is best if these letters are written specifically for this portfolio, with reference to your communication skills. A proposed program of study which includes a statement indicating the chosen minor or a petition requesting a specific list of courses outside the department comprising 25 credits. Also indicate which courses you have already taken and the grade you received. 12 of your 27 core credits must be upper division courses.