1. You have not Single Flavor Tested: Getting familiar with your flavor concentrates is the single biggest step you can take towards being able to quickly develop successful and appealing recipes. Like any other craft, you most become familiar with what you are working with. Your entire DIYing experience is going to be much more successful if you understand and appreciate the concentrates you are going to be using.

2. Accurate Measurements ~ Equals Consistency Whether by Weight, which requires using a precision set of digital scales that can measure down to .01 grams. This choice requires little effort, just start dripping your desired flavor concentrate into a bottle until you have reached your desired percentage in grams.

Or by Volume: Which will require blunt nose syringes on hand. Using separate syringes for each flavor is of great benefit when filling up the bottles. You will be using milliliters as your percentage of measurement.

Dumping or measuring flavor concentrates by drops is a mixture for disaster. You want to have a consistent quality product. One that provides a quality E-liquid now and in the future. Eyeballing, Guessing and Drops can not provide the same level of quality. You want a reliable and accurate way of measuring your ingredients.

3. You are trying to Clone Commercial E-Juice: Everyone wants to recreate some of their favorite e-liquids from various vendors and merchants. You would think, these are the best e-liquid recipes to follow if you are looking to Clone one of your favorite e-liquids. In truth, most clone recipes fall way short of the mark. What I have found is most commercial juice is over-flavored and over-sweetened.  This is one of the reasons I started mixing my own e-liquids, I couldn’t find E-liquids I wanted to vape that didn’t taste off, weird, or just too sweet. I also didn’t enjoy my coils being so gunked up (back in those days of 510 bridged atomizers that were $20 a 5 pack) making me change my coil every day, sometimes twice a day, it got expensive fast.  But even with today’s equipment, if I’m using premade coils or making my own coils, I am not having to rewick cotton once a day. In fact, many times I go as long as a month before rewicking by builds. I stopped trying to replicate other Mixers recipes. And started to mix to suite my own palate. I mix using cleaner flavors that are stronger and aren’t presweetened with sugars or other things. I truly believe when you start trying to create your own E-liquids, versus trying to recreate another Mixer/Companies E-liquids. That is when you begin to really enjoy the hobby and the overall experience of DIYing. 

4. Ingredient Substitutions Going off-recipe is a fun and creative part of the DIYing process, for sure. But it also requires a little more due diligence on our part to understand how the additional or substitute ingredient will affect the recipe. Remember cutting out one flavor concentrate then substituting it with another will give you a very different result than the recipe author intended. Not a bad thing. No, as long as you have a good working knowledge of how the substitute ingredient will affect the mix. Refer to Number 1# above.

5. Using Too Much Flavoring Kills Your Recipe So how does over-flavoring kill your recipes? If you enjoy complex style recipes you will end up with a muddled mess if you’ve over-flavored. It may be muted. It may be harsh.  Even simple recipes that are over-flavored can suffer from these problems.  Over-flavoring is one of the most common reasons for harshness, next to bad batches of peppery harsh nicotine. The other unpleasant side effect of over-flavoring is that it can cause you to go flavor blind (not able to taste a flavor anymore) far faster than if you had not exposed yourself to massive amounts of that flavoring aroma. Always start at a lower percentage in mix, check recommendations on percentages from the manufacturer and other experienced mixers & become familiar with how your flavor concentrates work together. Many times, less is more.

*copied from a  ELR source not written by me.