Since I DIY just for myself and friends I don't get as technical as I would if I was making it to sell. I have mixing bottles that I marked with permanent marker at 5% and 10% intervals. When I want an ingredient less than 5% I count drops for those. I know this is frowned on by the "experts" but it works for me and keeps it simple and fun.
I wear gloves, keep a sanitary surface and utensils and plan on using a dust mask in the near future. I feel more comfortable vaping my mixes than not knowing how vendors handle their mixing and what their sanitary practices are.
Marking the bottles is a great idea, and I already have gloves. I would dare to say that anyone who frowns upon your method hasn't been a woman in the kitchen cooking all of her life LOL. And thank you for making me feel welcome to ask questions, I'm sure I'll have some but will post in the non recipe thread