B R U S H E S a n d o t h e r t o o l s f o r a p p l y i n g p a i n t 
The bigger the better, is the general opinion when it comes to brushes.
Sable brushes are recommended to watercolourists, they keep a lot of water and form a
fine tip when wet. You can paint the largest and the smallest with the same brush!
Expensive, but good.
I like to use french watercolour-brushes (Raphael or JAX). They are of squirrel hair,
have a wooden grip
and a wired rubber tube that keeps the hairs.
They're durable, carry loads of water and form a fine tip.
They are a little too soft for precision work, but lovely to work with.
For details and signature I use synthetic brushes.They are hard-tipped but don't hold that much water,
which makes them better for lines than areas. 
There is a brand called Da Vinci that has a huge round brush with mixed hairs.
It's called Cosmotop and is really nice to work with. They kepp lots of water and are suitable to
splash and smash colour with.
There are flat Cosmotop from DaVinci with a red grip. They form a razorsharp line when wet.
Never again shivering, bent houses, treetrunks or boat masts. You can keep the brush upright
and "stamp" out lines, one after another. Sharp and thin. Lines, planks, horizons.
Oxhair flats are perfect to pre-wet the paper or paint loose skies. Not as sharp and straight as
Cosmotop, but keep a lot of water
.
Brushes aside, there are endless possibilites. Scrape, stamp, direct colour with sharpened
bamboo sticks, cakecutters, palette knives, razorblades, pencils, brushgrips, crumpled paper,
sponges, twigs. In wet paint, dry paint, before painting, after painting.
To apply masking fluid, I recommend that you DO NOT use your regular brushes. The fluid will dry
and ruin the brush. There is a tool called a Colour Shaper that has a tip of silicone. Once you're
done applying the fluid, you can just roll the dry fluid from the tip.
