A very important part of the application process that is often overlooked is the Letters of Recommendation portion. There's nothing like a fully equipped, all around great application that is accompanied by poor letters of recommendation or even just mediocre ones.
Some common questions that I had when I went through the application process were: Who is supposed to write a letter? What are they supposed to say? How long should they know you for? How do you ask them? How involved am I supposed to be in the process? The problem is a lot of these questions can be properly answered in different ways! Different strokes for differed folksdepending upon the situation.
Who is supposed to write a letter of recommendation? A letter of rec should first and foremost be written by someone who knows you, has seen you operating well in the workplace, academia, service etc. and you are 100% sure can write you a letter that will CONVINCE an admissions committee that you belong in their class no matter what's on your application. In my experience, I had a science professor, MD, and service trip instructor write my letters. For PA school, they often recommend or even require that at least one letter is written by an MD or PA so keep that in mind as you shadow and make connections with medical professionals.
What are they supposed to say? How long should they know you for? The first question is kind of up to you and your writer. Some writers will involve you in the process and some will choose not to as a formality. Always at least offer up your credentials and resume or some things you're proud of that they may not know about. The second question is also up to your discretion. I feel as long as you are able to make a genuine connection with them and they know your passion for the profession, they should be able to translate that onto paper. I would stray away from asking someone you've shadowed for one day, an advisor you've spoken to once, or a teacher who you never visited during office hours. Attempt to build relationships outside of the classroom, workplace, etc. so that they can really get to know you personally.
How do you ask them? This can be awkward to ask even one of your closest mentors! To ask someone to, in essence, evaluate you and write the best things about you can be nerve wracking! I asked my writers through email just because I think it's a more formal way to write my thoughts. Also, because one of my writers was not in the same city I was in when I needed it. After getting their agreement through email, I was able to meet up with two of them in person to give them more information about my background, resume, and things they should touch on in the letter.
How involved am I supposed to be in the process? This should be decided by both you and the writer. One of my writers really involved me in the process by pretty much writing it with me in the room, while the two others took my information and background and went on to write it on their own. I've also heard of applicants literally writing their own letter of recommendation, running it by the person they asked to write it, and giving it to them to submit it online to CASPA.
Thanks for reading, and happy searching for your letter of recommendation writers! I hope that this is a helpful start!