Filets have a look!
1- to keep the colours fresh place the colours down and try not to move the brush to much were colours meet …its the mixing on the paper that makes them go murky
2- The scamp allow you to practice the shapes of each element of the painting and the the pdf line drawing will help you but its best to go with the flow of the painting i.e. if a leaf looks good some were else…then do it there
3- Use the tissue mainly to lift off excess water areas when they emerge and to lift off and soften areas , not just were paint merge.