This might help.
You should understand how light interacts with objects of different kinds. I mean the physics model.
Material absorbs, reflects and refracts light (and probably does other things to light).
Really understand what it means to be 100% reflective or 100% transparent (refraction changes the direction/angle of light rays/photons, which can also vary in strength).
So 100% reflection is a mirror, which is made of a very thin, very smooth
layer of metal protected by glass on top.
To draw mirrors, understand the principle how every particle - when reflected - is reflected at the same angle relative to the reflection surface as it had right before it hit the surface.
If the surface is rough, the reflection is blurred.
If the surface is convex it starts to reflect more off the surrounding, while the viewer sees it as distorted from his vantage point.
Transparency is easy. Just lower the opacity of the wash or mix the paint for the spot with the color that's behind.
For glass in front of a brown bear, you would mix the brow n of the bear with the color of the light that is reflected off of the colorless glass. Less brown in the mixture as the reflection increases in strength.
If the surface absorbs part of the light, the surface becomes darker and the complementary color to the absorbed wave length becomes visible.
Refraction is the distortion of light which becomes very obvious in water or other mediums with a different density as air at room temperature.
Hot air --> fata morgana, because of the distortion of the light send out from the distant object (be it a diect light source or an indirect light source through reflection).
Water --> things seem offset by a certain angle when looking through a flat water surface. Round off the surface using a glass jar or waves, you'll get all kinds of fascinating distortion.
Play around with the composition of those main three properties
(- roughness and texture, which is part of reflection)
You can study those properties a life time if you want to understand them more and more, and how they interact with each other. Then you can start to also play around with the color or the light and the color of the object.
Maybe a hourglass shaped glass container, which is semi transparently green in front of a yellow cube lit by a point light source a few feet away to the top right, which has a slightly blue color, while the surrounding has an overall purple atmosphere, while parts of the glass are rough and have scratches.
There is a lot of fun to be had.
When working from imagination, most people put down blobs of color which are informed by these principles until it looks right. But it's important that you could go in and actually make it photo realistic if you wanted to. But usually it's not worth the effort. There comes the question of why you are doing art and what kind of goal you're trying to achieve.
- t. got bitten by a viper man who wrote this with one hand