Register to take the Graduate Record Examination, also known as the GRE (see Resources). This should be done in September, and you can spend the month preparing to do well on the GRE, which is administered in October.
Research Ph.D programs in Psychology to determine which schools are best for you. You may wish to consider Psy.D programs as well (see Resources for more details on how to choose the most appropriate school). Go beyond a Web search to speak to the faculty in those programs and visit their campuses.
Submit transcript requests to your undergraduate college. Have them sent directly to the programs you are applying to.
Contact references and ask them to write letters of reference on your behalf. Your references should be academic, such as professors in undergraduate classes who are familiar with you and your potential, although some schools will accept letters from non-academic references like clergy or former employers. Send your references an updated CV and statement of purpose so they have some additional material to support their letters. The letters should be sent directly to the schools you are applying to, although some programs prefer that the applicant send them together with the application form, in sealed envelopes with the signature of the reference on the seal.
Complete the application forms, in particular your statement of purpose, and send them off to the programs of your choice. To meet deadlines, these steps are usually completed by the end of December. Be sure to keep a full copy of all application materials for your records, just in case something gets lost. Include any financial aid applications.
Follow up with your references in early January with a thank-you note for writing letters on your behalf. Not only is this polite, it also has the benefit of gently reminding them to write them if they have not done so already.
Accept an offer of admission from one of the schools you applied to. Letters of acceptance should be sent out in March.