If you'll browse several pages of discussions on the DIY Eliquid forum, you'll see many containing tips, recommendations for where to buy DIY supplies, ones containing recipes, etc. There is an abundance of the info. you seek. There's 1 discussion in particular that is loaded with recipes. It's the "Recipes for Dummies" thread.
About the mixes you've made so far - I personally don't make just single flavor eliquids. Most eliquids (store bought ones & DIY ones) require using a variety of flavoring types (ie. primary ones, secondary or blender ones, and accents, sweeteners, etc.). It's made using a recipe (like for cooking or baking anything)...and it takes a variety of different types of ingredients to make it. For example: Even a simple tuna salad sandwich isn't made with just tuna fish and bread. Most people will use mayonnaise, maybe some pickle relish, some chopped up hard-boiled egg, or chopped up celery, a little salt and/or pepper etc., too.
Edited to add: IF you went to the Deli section of a grocery store though, and bought already made tuna salad (which includes the ingredients above)...all you'd have to do is spread it on some bread, maybe add a little lettuce, and eat it. That deli tuna salad is comparable to the type of flavorings below, that some vendors sell. They will identify them as being ready-to-use, already blended/mixed flavorings that you add to your PG, VG, and nic base.
There ARE some types of flavorings that ARE ready-to-use singly to make eliquids when you DIY. That's because they already contain the mixture of flavoring types needed to achieve a specific taste or flavor you want. So all you do is add a certain % of it...to your own PG, VG, and nic base.