When I make up my AA-Lysine-Mg citrate drinks I typically rub some on my face.
I have in the past made this up for others and have used grapefruit seed extract as a preservative with mixed results. Probably better to make this fresh on a regular basis to maintain efficacy levels than to store for repeated use.
I don't notice much, but others (who don't megadose AA) love it and report that it leaves their skin feeling tighter and refreshed.
I take the vitamin C powder and dissolve it in some distilled water. Then I add the glycerin. 1 part (1 TBP) glcyerin to 3 parts of water. (3TBP) I add in 1/2 to 1 tsp of vitamin C. Put it on before you go to sleep.