My eyebrows are already kinda thick,but they would be better if they were thicker.I'm interested in starting to use minoxidil,but from what I understand,it's a product for people over 18.I've also heard of castor oil,but it's not as effective as minoxidil.If possible,I will use these two.I would appreciate it if someone could tell me how to apply them safely,and what brands do you recommend?