To get a BA in philosophy, research university programs. Research not only the curricula, but also libraries and faculties. Find teachers and mentors with whom you can develop a productive relationship; this is more important than school rankings.
Begin specializing in a particular area early. Philosophy is a vast field, and if you try to study all of it, your knowledge will remain shallow. Sacrifice the stoics for Heidegger, or vice-versa, if you intend to reach a depth of knowledge that will be useful.
Focus your undergraduate efforts on preparation for graduate school. If you are serious about philosophy, a BA is really only a stepping stone toward your Ph.D. If you are at a school with an undergraduate thesis option, take it. The BA thesis will make you a more attractive graduate school candidate and will give you valuable experience for future research.
If possible, enter a Ph.D. program directly from your BA. Some universities allow this if you were an outstanding undergraduate student. Other universities require a master's prior to entry in the Ph.D. program. Consider your options well in advance so that you are not rushed into a decision. Enter a North American Ph.D. program only if you are prepared for several years of coursework, followed by your research and dissertation.
Research European programs that offer "research only" Ph.D.s that have no class component. A Ph.D. can be completed in England in three years. In addition, tuition is substantially less than in the United States. For those with great ambition but less time and money, European study is a good option.
Write your dissertation as an original contribution to knowledge. A dissertation must be more than intelligent, cogent, and well written. It needs to be based at least in part on original research and primary sources. Consider the location of your university of choice carefully. If you are researching a particular philosopher, find out where his archives are, and be aware that you will probably need to access them as part of your research.