I have been drawing and painting since the past 5 years now, I did it in O levels, all through A levels and I now study in an art college.
Practice makes perfect
Through all this I have realized, time and experience are 2 different things, its the frequency of practice and not the time you spent on it. The more you do something the better you get at it. Art in the drawing and painting medium call for vision and not sight.
1. Sharpening your memory
Visualizing what you have to make in your mind, to perfection and then putting it on paper needs lots of practice and attention. One of the best ways I have learned to do that, is to make from memory. And a practical way of doing so is by placing you still life, or whatever else you want to make far away from your workplace, what happens now is, you go to your still life observe a certain section of it very carefully, and come back to your workplace, take it out of your memory and put it on paper.
Yes, it takes time and exercise, you go back and forth frequently, but the hard work is worth it, since it sharpens your memory. In no time you shall be able to accomplish minute details, just by what you have restored in your mind, your trips to your still life will cut down and you will be able to draw more in one sitting.
2. Making from Memory
This is a very complicated yet simple thing to do. What you have to do is read a detailed excerpt, with lots of visual details, and translate it into an image that you see while you read. Everyone has their own perception of things, their own way of imagining.
But however a better way to create what you have imagined, especially if your imagination is not that strong, is to google up some images of the objects that were being talked about. And see which best suits what you first visualized and put that together to make what makes the best image of the excerpt.
This is one of the best techniques to make your drawing and observation better, in other words this is what constructs your vision of the world, and how you see it.