A good way to start is one drop base, 2 drops mid, 3 drops top. Or you can get quite scientific - I've actually started doing this for my signature scent I'm developing and it's kind of fun. First, mix 2 top notes in 10 different concentrations, by drops: Note A: 10-9-8-7-6-5-4-3-2-1 Note B: 1-2-3-4-5-6-7-8-9-10 So your first sample is 10 drops A, 1 drop B. Your second sample is 9 drops A, 2 drops B..... You've got 10 samples of 11 drops each, with note A the strongest in the first sample, and Note B the strongest in the last sample. Figure out which one you prefer, and make up a mixture using that ratio. Next, using that mixture, add in the mid note. Mixture of A/B: 10-9-8-7-6-5-4-3-2-1 Middle note C: 1-2-3-4-5-6-7-8-9-10 Figure out which one of those 10 variations you like, and make up a mix of A/B/C. Continue on with the base note... Takes a long time to work through though