Colours are dull and muddy
This is usually caused by the overuse of brown tones like burnt sienna and ochres. Another contributing factor might be not having clean water for brushes so every colour is being muddied. I have also seen learners not allowing an under-layer of paint to dry so that the colour layered on top mixes into it, which is not always the desired result. One way to solve this issue is to mix your own browns from the three primary colours (red, yellow and blue) and mix a range of neutral tones rather than using neutral colours straight from the tubes.
You can’t mix the specific colours you want
Colour mixing is a skill which comes with time and the way to learn is to mix all the colours from the three primaries (red, yellow and blue) and avoid using too many secondary and tertiary colours from tubes. Try mixing colours before on the palette and trying them out on a test piece of paper (colours can look different on paper to the palette).
I also have another trick to help identify the subtle changes in colour that can be hard to see. If you are painting something that is all the same colour for example green but there are many different greens there, you can use a colour identifier to work out the slight differences.
Out of proportion
When artwork just doesn’t look right it is often because it is out of proportion. Look at the comparative proportions, this means how long, wide etc. one object is in comparison to the other(s). It is well worth spending time planning out the drawing before starting on the painting to help this issue. You can also look at the negative space around the subject. If you are struggling with this problem constantly you could also use a grid. I shall be writing a post about using grids and scaling up so look out for that one.
Does the artwork just lack something? This is often due to a poor composition, things are too regular, placed in the middle of the page or just too uniform with no focal point. Rethink the composition, try out a few possibilities with thumbnail sketches before you paint. Consider a new viewpoint, you could look up or down, or choose a viewpoint from behind a door, an extreme close up or more distant view. The best way to find more interesting compositions is too experiment, using a camera is a good tool for this too.
Lack of tonal range
If your artwork just looks flat and doesn’t really have a great deal of impact it could be due to lack of a tonal range. Contrast – lots of very dark and very light tones creates a sense of drama and depth. Often beginner artists draw in a range of mid-tones and avoid the darker tones that could make the subject look more dramatic and three dimensional.
There is a time when you should finish a piece of artwork but for some of us we don’t always get this right. This leads to overworking and the artwork starts to look stale and lacks the vibrant look it may have started with. Overworking is a common problem because we want to work until the artwork is ‘right’. Moving onto another piece is always a better solution, if you must come back to a piece leave it a few days so you have fresh eyes. Learn when to move on!