Once you know your area of study and desired degree, the most basic considerations in selecting graduate programs to which to apply are location and cost. Many faculty will tell you to not be choosy about geographic location but remember that you will spend several years in graduate school. Be aware of your own preferences as you consider graduate programs.
Not all graduate programs in a given area, like clinical psychology, for example, are the same. Programs often have different emphases and goals. Study program materials to learn about faculty and program priorities. Are students trained to produce theory or research? Are they trained for careers in academia or the real world? Are students encouraged to apply findings outside of academic contexts? This information is hard to come by and must be inferred by studying faculty interests and activities as well as examining the curriculum and requirements. Do you find the classes and curriculum interesting?
Who are the faculty? What are their areas of expertise? Are they distinguished? Are they all about to retire? Do they publish with students? Can you see yourself working any of them, preferably more than one?
There are many things to consider when choosing graduate programs to which to apply. It may seem time intensive and overwhelming, but putting in the time to carefully select graduate programs will make it easier later on when you are accepted and must decide where to attend -- that decision is much more challenging.