You know the old saying, location, location, location? Well it is true, where you choose to take your pictures is a pretty important choice. Not so much the specific place but more the flavor of the place you choose. It's best if your location reflects your personality. If you aren't sure about a place, please ask your photographer for some suggestions. If you do, please help them out a bit by letting them what type of places really speak to you, let your preferences be known. Are you a beach person? Make sure they know that. More of the woodsy sort? Don't be afraid to speak up if they suggest a beach location instead. Another suggestion is to check out some of their other pictures to see which ones appeal to you the most.
Just as important as the location of your shoot is the timing of your shoot. By timing, I mean both the time of day and the time of year. I plan my shoots either earlier in the morning (approximately 2 hours after sunrise) or later in the afternoon (about 2 hours before sunset). They differ partly because the sun gets harsher as the time goes by in the morning whereas in the afternoon it gets softer as time elapses. but it also becomes a race against the setting sun and ultimately darkness. Also it is important to take into account whether or not you are a morning person. Remember you have to leave time for getting ready so if it is 2 hours after sunrise, a morning session is probably not a great idea if mornings are not your favorite. In addition to time of day, time of year is also important. If you are a beach person and want to be nice and tan for your portraits, then summer is probably the best time for you. Love sweaters and the fall colors? Then your best bet is probably to schedule something in the fall (please note, whatever your choice, you should contact your photographer in plenty of time to make sure they have availability). Be ready to be flexible though, this past senior season, I had a senior choose the fall because she's a self-proclaimed sweater girl. Unfortunately, the late September day that we chose ended up being unseasonably warm. No matter, she still rocked the sweater!!
Try to bring at least one classic outfit in classic colors. Solids generally work best as well. I realize that you want to show off your unique fashion sense and I encourage that but I also think that it is important to also have some pictures that will stand the test of time. Once those are covered, then you should definitely plan an outfit that is 100% you. I encourage you to bring your favorite outfit, no matter what anyone else says. Most photographers will allow you at least one outfit change so take advantage of this. My policy is to let you change as much as you want. Speaking from experience though, I have found that any more than 3 outfit changes tends to get a bit overwhelming, 3 seems to be the optimal maximum for outfits. Also accessories can be a great way to change the look of a classic outfit quickly.
By all means, bring some with you. I have had seniors bring uniforms, sports equipment, color guard flags, instruments, favorite books, favorite sweatshirts, pets, those are just some that I thought of off the top of my head. I, and most photographers, firmly believe that the more personal your session, the better.
I am a low maintenance kind of person, I can count on one hand the number of times that I have worn make-up, so I certainly don't consider myself an expert on this. My rule of thumb would be to do what will make you feel confident and comfortable. If you want to get it done professionally, go for it. If you would be more comfortable doing it yourself, then, by all means, do that. I have had seniors do both, to much success. The only recommendation that I would make is that if you are going to have it done by someone else, then it is probably a good idea to have a test run to make sure that you are both on the same page.
To bring or not to bring:
Someone with you, that is. Again, this depends on your own personal preference. I have had seniors come alone and I have had senior bring someone with them. There are benefits to bringing someone with you: you have someone to offer opinions and perhaps more importantly, carry your stuff. Moms are always good to bring along, just saying, (although there is a slight chance that I a little biased about that one). Then again, some people are not comfortable with an audience, if that's you, then it may be best to plan to fly solo.