All good things come to those who wait. Tip number one for improving your drawing skills, is patience. It has to be right here, the first, number one! Especially so with colored pencils, but in truth with any drawing medium. The biggest thing that pulls down most artwork is not lack of skill, but lack of patience.
It's hard right? You have spent hours on the eyes or the petals or the nice little part that catches the light and now you have to draw the fur or the hair or the grass and you start with good intentions but it gets a bit tedious and then it gets a lot tedious and then .... well, you just want to get it finished and start the next piece. Stop. Right there. Notice that moment it starts to feel tedious. This is the moment that you choose whether you are going to draw the most amazing piece you have ever drawn or whether you are going to produce a pretty mediocre piece and tell yourself that you never get any better or that you are just not that good.
Patience is the difference between 'blurgh', 'okay' and 'wow!'. It doesn't matter how long you have spent on the amazing eye, the stunning petals or the glistening gem, if you have scribbled the fur, rushed the hair or sped through the background, that part you spent hours on will not look anywhere near so good. Imagine going to a Michelin starred restaurant and being served your meal on paper plates with cardboard cups and plastic knives and forks because they are trying to save on the washing up. That is what you do to your art when you rush.
l am not saying it is easy, patience is the hardest thing to learn, but learn it and you will also see some of your biggest improvement because it is patience that makes you keep going, adding another layer, another colour, refining a bit here, rechecking your reference photo etc. And if you ever hear yourself saying, 'that will do' that is a certain sign that it won't and that you can do better.
I know for certain that when l have finished a piece if l have rushed any part l will forever look at it and wish that l had spent just a bit longer working on it. I have never looked at a piece and wished that l had rushed a part. The extra time is always worth it. Take it. Be patient and see the difference right away. I promise you, the more patience that you learn the better your art will be!