DIY is great. I have some nicotine that I use to up the strength of my 3 mg/6 mg juice, and I like the flavor company Flavourart. Their flavors are more concentrated than those of some other companies. My favorite by them is Soho, which is one of the few that isn't very concentrated - I mix mine to the recommended 20%, but most FA flavors can be mixed much lower than that. May I also suggest a digital scale? I find it easier to mix by weight instead of volume, and it makes mixing very simple and accurate once you get the hang of it. It's easier than counting drops, and possibly easier/faster/not as messy as measuring by volume. A good digital scale isn't that expensive either, maybe $30 on amazon. If you get one, make sure it measures to a hundredth of a gram.
Regards and welcome to the forum.
Regards and welcome to the forum.