I think the thing to remember when filling out applications, writing thank you letters after your interviews and to the writer's of your LOR's, is that you are applying to a professional school. So what will help impress people about your maturity level and seriousness is to treat it as such.
The suggestions that I received when I was applying, was to:
1. Type everything. Do Not handwrite. This was a pain since I had no typewriter. So I just utilized the one at the hospital I worked at, and on a couple occassions I went to the public library.
2. Do not use paperclips for your photos. I think it would be fine to attach checks and additional info by paperclips, but your photos should be glued or taped in the space provided. If there is no space allotted for a photo, and there is no specific instructions for attachment, then go ahead and use a paperclip.
3. Always remember that following instructions is crucial. The application process also tests to see how well a potential student can follow instructions. If you fail to adhere to what the school wants, this may be a yellow flag to an adcom. Some schools might worry what will happen when you are in school and/or on the wards.
4. Remember to relax and try to enjoy the long arduous application year. In many ways it's worse than preparing for the MCAT.
These are just suggestions, but by doing this I think the worst that can happen is that you may impress someone.😀