If you can cook you can make DIY. If you wanted to make a lime cheesecake, think about what you would put in?
Get
ejuice calculator, do all your tests with PLAIN vg/pg solution (no sense experimenting with higher priced nic solution). Write down your percentages, let it steep, try it and decide what it needs.

Lime cheesecake, um, lime, cheesecake, vanilla custard flavoring..try that and tweak.
Really same as cooking.