When I get ready to mix, I stick the recipe in my calculator here. I name it something that somewhat describes the flavor to me. I put that exact same name on a label with the date and mg. I mix, put the cap on followed by the label, and into the closet it goes for a day or so. I keep fresh mixes in a row at the front of my shelf. I vape a sample of the bottles in this row then they go to the back of the shelf in order by date. I did manage to get one bottle not labeled when a friend was over mixing with me. I made up 30ml of a recipe and forgot to label it. But I knew what day I made it. So all I had to do was go to my page and look at the date. The one I made 30ml of was enough to tell me that was it. But it was also the one recipe I didn't have a bottle labeled after. Sorry, long story.
I have a 250ml flask I use when I want to mix mad volume. I still mix by weight. I haven't used a syringe since I first started mixing. Way, way, way too much hassle. The syringes are nice to have if you want to check the weight of a flavor you have suspected of being off. But I have yet to find one I am too worried about.
@Borders_03 - I would suggest you buy This Scale or This Scale and plan on mixing by weight. Using the syringes, you will waste more flavoring than you get in the bottles. Other than that you may want to pick up a cheap flask set like This One. And eventually you may want to store your flavors with something like This.
Hope this helps.