So you booked a session but you aren't sure what to wear. I always tell people to take into account the location and weather that is forecast for your shoot. If it's 100 degrees and you are doing some branding shots you probably don't want to wear a wool blazer or you will appear sweaty in the images. Stripes.....I have met "very few" people that can actually pull off a look wearing stripes, so be very careful if you choose to go this route. I am reminded by one of my siblings about the "pants" that my mom made them wear growing up which had stripes, it definitely is an acquired taste!
Whether it's an engagement session, senior or branding session most people typically have a couple of outfits they would like to use. It's always ok to bring extra outfits in case the background setting is not complimentary of something you thought you would wear. I have had clients bring 5-6 outfits with the intent of only using a couple of them. In my experience couples doing their engagement photos tend to bring a dressy outfit and then a more casual one just to mix it up a bit.
Senior photo sessions if you have something you want to incorporate in your photos please bring it with you, unless it's a horse or something and then hopefully I am coming to you for the session. For example if you were active in a sport, you might bring a letter jacket, or a volleyball, a football, baseball jersey, etc. If you were a marching band member your instrument may be appropriate.
I typically don't recommend wearing white but some clients have their heart set on it so we will have a conversation prior to the session so that expectations are met on all sides.