One of the biggest things when you're applying makeup is making sure that your makeup is blended properly. Here are some tips on how to achieve this. I would say the main thing is having the correct brushes. If you don't have the correct brushes, you're not going to get the end look that you're going for. Also, make sure that your brushes are clean. That's another thing. I always clean my brushes. I have a daily brush cleaner that I spray on, and wipe it on a tissue. It keeps them clean, and also sanitizes them. I also shampoo them once a week.
Another trick to making sure that your makeup is very well-blended is to use a setting powder. You can use that last, and dust it on. It blends everything, and smooths everything out. One other thing that I would suggest when you're working on eyes is working from lighter colors to darker colors, because it's easier to blend dark into light, rather than light into dark. And those are my tips on keeping your makeup blended.