1. Wet-on-wet and wet-on-dry
Painting wet-on-wet means that you first wet the area which you want to paint and then add paint to that area. With this technique you can achieve very soft washes of color without hard edges. As you can see on the third picture, you can also mix two colors easily. Painting wet-on-dry means that you don't pre-wet an area first; you just paint straight on dry paper. You can also mix colors with this method, but you will get hard edges and you won't achieve that smooth look as with wet-on-wet technique.
2. A graded wash and a flat wash
A graded wash is a gradient of a color. We can see a change from a darker tone to a lighter tone of a color in a graded wash. A flat wash is done in one tone and there is no transition between light and dark. These two techniques, plus the wet-on-wet and wet-on-dry techniques, are crucial to learn. In the third picture you can see a part of my peony painting. Can you guess which techniques I used? The petals were painted first with a graded wash - you can see transition from a darker to lighter tone of pink. Some areas, like the middle part with strong dark pink, were painted wet-on-dry with a flat wash technique. When the petals dried I used the wet-on-dry technique to paint the veins. The yellow stamens were firstly painted wet-on-dry with a flat wash. When they dried I added darker shadows with the wet-on-dry technique.
3. Negative painting technique
With this technique we can get really beautiful and interesting effects. It may be difficult to understand at the beginning, but it's really worth practicing. In this technique you don't paint your object but instead you paint the background. I made a video about this technique. You can watch it here. In these three pictures you can see the examples where I used the negative painting technique.
When you splatter an alcohol on a wet watercolor paint you will get interesting spots. The best alcohol for this is vodka.
Be creative. You can use a brush to splatter drops of vodka on the watercolor surface. You can also use other tools and check what effect you can get. Vodka pushes the paint away and leaves lighter spots. Think how you can use this technique.
5. Plastic wrap
With plastic wrap you can get a really nice effect. First apply your paint on your paper. While the paint is still wet use plastic wrap (try out other kinds of materials too, like foil) and place it over the wet paint. Use your fingers to move it around in a way you like.
Leave everything to dry completely and then take the plastic wrap off. As you can see in the picture below, foil leaves beautiful marks. Think how you can use them. Frozen surface of a lake? Maybe water?
6. Clear water
Clear water works similar to alcohol, but alcohol is much stronger. Nevertheless, you can use clear water to get lighter spots. This technique is hard to control, but you can achieve nice effects.
7. A toothbrush
In my tutorial with a cactus you can see how I used this technique to create an effect of sand. I used it also to create texture on the rocks. Dip a toothbrush in a puddle of paint and, using your fingers, splatter the paint on the paper. You can cover some areas if you don't want the spots to get there.
You can blow a bead of a paint in order to get a branch-like effect.
You can scratch your paper a bit with, for example, a palette knife. You can also use a scalpel to scratch tiny highlights. I wouldn't use this technique much because you literally damage your paper, but sometimes it can be useful if you like to experiment a bit.
10. Cotton buds
They absorb water very gently. You can use them to make lighter spots.
11. Masking fluid
This is something I couldn't live without. Some watercolor purists say that we should not use masking fluid. I say that if it can help, then we should. Why not?! Masking fluid (also called "frisket") is latex-rubber fluid that can be used to preserve some areas from being painted. I can not stress enough how handy it can be. I will refer again to my cactus tutorial where I used masking fluid on the spikes. It would be just impossible to paint it without masking fluid (in fact it would be possible, but it would take much more time and effort).
Masking fluid can have different colors. The one below was white, but I also had blue and yellow. The masking fluid which I use now (Liquid Masking Film by Talens) is dark grey and I highly recommend that you buy darker frisket. The reason for that is that when white masking fluid is dry you can't see it on the paper. Grey is clearly visible and this property is really important.
One important thing when it comes to applying masking fluid is that you shouldn't use your good brushes. Masking fluid, when dry, is like rubber and glue - it damages bristles; it sticks the bristles together. I usually buy very, very cheap brushes, specifically for masking fluid and I use them once or twice. Depending on where you want to apply masking fluid you can use other tools like a knife, a ruling pen, a nib or even a finger. One more tip: If you use a brush, dip it in water, then rub a brush on a bar of soap and then dip it in masking fluid. Soap can help you to maintain your brush in good condition a bit longer. Here you can see the examples of how masking fluid works:
You can also splatter masking fluid with a toothbrush or a toothpick. Try out other tools too.
Depending on the size of the salt crystals we can get various effects. Salt should be sprinkled when the paint is till wet.
Take the salt off only when everything is really dry, otherwise you can damage your painting.