I try samples one at a time, unless I have the rare (for me) luxury of a whole day at home. On those days, I might try four (two wrists and two backs of hands).
Lately my samples got out of control (too many), so I put them in baggies labelled by house name (A-D, E-H, etc.).
Like several others here, I keep a spreadsheet for notes. I list House, Fragrance Name, Notes, Comments, Rating (1-5 stars), and a column in which I place my initial -- or not. The initial means that I feel the fragrance is "me" and that I might want to buy a bottle some day. I am going to add a field for Perfumer some day.
Sometimes, I just can't decide and make a note to do a second or third wearing.
When I do buy a bottle of something, I try to keep the sample vial and refill it as needed for my purse.