First, consider what you might do with a Bachelor's degree in Sociology.

a. Do you need to recharge your batteries?
b. Will the skills you will learn in the work force help you to be a better student?
c. Will a full time job help you to develop confidence in yourself?
d. Is there a field that interests you?  Do you want to work in it before entering the field’s professional schools to make sure your interest holds over time?
e. Will the work-a-day world help you to develop motivation for graduate work?
f. Do you have the money to enter graduate school now?

a. What career do you want and what degree does that career require?  Teaching high school requires an MA, but a PhD provides relatively little benefit.  Teaching at the college level requires a PhD and the salary is higher.
b. How much do you enjoy doing research?
c. How able are you at managing your own time?  Can you work without formal structures enforcing deadlines?
d. How good are your credentials?  A middling college student is more likely to get accepted to an MA program, and at most schools you can use an MA to springboard into their PhD program.  There is always the danger, however, that your credits will not transfer if you switch programs/schools after your MA.
e. Doctoral students get most of the financial aid, so an MA may be a costly endeavor.

a. What resources does the school have?  Workshops and centers?  Conferences that offer an opportunity for professional development and publishing? 
b. Happy graduate students? 
c. Graduates placed in jobs you might want or respect?  Graduate students who graduate? 
d. Professors working in fields (or sub-fields) that are of serious interest to you?
e. Ask professors at your school whom you respect for the names of good programs and good advisors in the area you want to study.
f. Add the names of academics whom you have read in classes, and enjoyed. 

What aspects of a department should I consider important?
a. Prestige of the department
b. Substantive emphasis of the department.
c. Attrition policy.
d. Time to completion.
e. Placement success.
f. Emotional quality of the department.
g. Logistical resources: Will you have access to a word processor?  Is there money for travel to conferences?  Is there money to do field work?  Is there fifth- or sixth-year support to complete your dissertation?  Is there adequate lab space? 
h. What are the teaching requirements?
i. What financial support do they offer?
j. Are there language requirements?
k. What is the social climate?

In the best of all worlds, you will choose to apply to schools where there are specific professors with whom you would like to work.  How do you know whom you want to work with?
a. Read their publications.  Are they interesting to you?  Thought provoking?
b. Look at advisor’s own professional development.  Where were they educated?  Who are their collaborative colleagues? 
c. Talk to their graduate students: are they happy?  Are they progressing toward their degrees on schedule?  Do you like them?  Is their research progressing?  Do they feel the advisor has been helpful?  How or why?
d. Talk with them over the phone or schedule a visit to campus (which you should do anyway, if you can).  Ask them to explain some portion of their research.  Do you like their pedagogical style?  Is it condescending or pedantic, or is it provocative and enthusiastic?
e. Does the professor have tenure?  If not, how confident is he/she or his/her colleagues of getting tenure?

What tactics can you use to get this advisor to support your application?
a. Take classes with them in the summer or whenever.
b. Look for research assistantships, fellowships, summer research jobs or volunteer to help with research projects.
c. Pursue independent study.
d. Attend conferences.  ASA.  ESA.  Local university/college conferences, etc.
e. Visit prospective universities.
f. Write letters or emails.
g. Solicit introductions: ask professors to introduce you.

There was a study done by ETS (Educational Testing Service) where they surveyed how 12 disciplines at 151 schools judged admissions criteria.  They rated the criteria from 1 (not used) to 5 (extremely important).  Here is the average weight schools gave to several components of your application:
3.9 Undergraduate GPA in your field.
3.8 Recommendations from faculty known by members of the department to which you are applying
3.7 Undergraduate GPA in Junior and Senior year
3.6 GRE verbal score
3.6 Undergraduate major related to field of study
3.5 Overall Undergraduate GPA
3.0 Educational or career aspirations of applicant
3.0 Recommendation from faculty not known to department
3.0 Applicant known to departmental faculty
2.9 Other academic achievements: papers, projects
2.9 Quality of undergraduate institution
2.7 Personal statement
2.7 Impression made in personal interview
2.6 Work experience
2.6 GRE analytical score
2.5 Non-faculty recommendation Letters
2.5 GRE subject exam

a. Get good letters
b. Do well in your major, in your junior and senior years, and overall
c. Do well on the GRE
d. Project the right image in your essays and interviews
e. Research the department’s current emphasis and choose a less competitive field or sub-field.

Spring of Junior year:
1. Get catalogues
2. Get GRE information bulletin and purchase sample tests.  Can take the exam for the first time.
3. Talk to professors.
4. Identify and begin to contact and seek to work with potential graduate supervisors.
5. Solicit letters from professors.  Have the dossier service keep them on file until you need them.

Summer before senior year:
1. Choose which schools to apply to.
2. Get applications and catalogues.
3. Read material carefully.  Make a checklist of deadlines and a complete list of everything that you will need for all of the applications.  Note that many schools have two deadlines: one for financial aid early, and then a later application to the department or graduate school.
4. Verify your official transcript is complete and accurate.
5. Draft a statement of purpose.
6. Prepare a resume.
7. Take GRE practice exams
8. Continue to build relationships in the field
9. Visit schools.

Fall of senior year:
1. Complete your deadlines and application check list
2. File financial aid applications.  File Fellowship applications.
3. Fill out applications at least two months before deadlines.
4. Finish personal statement
5. Gather money for applications—about $500.
6. Take GRE.
7. Get all recommendation letters finished.
8. Mail applications at least a month before the deadline.
9. Call each school to make sure it arrived.

Studies have found that you are more likely to graduate if you are:
a. Married
b. Are on schedule finishing your master’s
c. Are in the sciences: physical scientists and biologists are most likely to finish, social sciences are in the middle and students in the humanities are most likely to drop out.  This reflects higher levels of collaborative research and funding in the sciences.
d. Are financially secure.
e. Have clarity of purpose
f. Have a good relationship with your advisor.

In 1991, the average time to completion for anthropologists and sociologists (National Research Council) is 12.4 years; the amount of those years during which normative students are registered is 9.1 years.