Mixing the plaster
Using a plastic bucket, sprinkle a measured amount of plaster into the same amount of water and stir with a wooden stick or ladle. Stir until the mix is lump free and a smooth creamy consistency.
A hand whisk is a handy tool for this job.
When satisfied with the mix, sprinkle water onto the 'spot board' (a flat board, about a yard square placed at waist height on a suitable stable base). Tip the plaster onto the spot board.
Loading the float or trowel with plaster
It is a good idea to practice loading the float from the hawk whilst your stood over the spot board as this will catch any spare plaster.
Scoop up and load plaster onto the hawk. Now, holding the hawk in your left hand, if you're right handed, (or visa versa, if you're left handed) at a level between chest and shoulder, set the blade of the float at right angles to the bed of the hawk and push a measure of plaster towards the edge furthest away from you. As you do this, tilt the hawk slightly towards you and follow through with the float in a scooping motion. This movement is carried out in one fluid action. Practice this until you are satisfied with your progress.
Skimming the joints
When ready, the first job is to seal the joints by spreading a thin layer covering the joint tape. Hold the float at about 30degrees to the plasterboard and move it in a smooth upward motion, in line with the joint. Use enough plaster to allow the mesh of the tape to be left just visible. When you have completed all of the joints the plaster on the first joint will be dry enough to start skimming the boards.
Skimming the boards
Working from the floor level upwards, spread the plaster thinly (about 1/8" thick) in vertical strips, stopping just short of the ceiling, then work downwards. Tuck the float into the corner at the ceiling and then work down to meet the upward sweep you have just spread. Keep clear of the taped joints on this first coat.
Applying the second or top coat of plaster
When you have finished this first coat, you should be able to begin applying the second coat using long sweeping strokes to eliminate any ridges. Starting each sweep at the bottom corner of the wall and work along to make one continuous coating. After the wall has dried a little go over the wall with a clean float smoothing any marks or ridges, making sure to get all the way into the corners.
When the plaster has hardened (but not dried) "polish" it using a clean float. Use a wide paint brush to sparingly splash clean water on the surface as you go. This acts as a lubricant for the trowel and allows it to pick up a fine film of plaster which fills any minute holes.
If you wash your tools at regular intervals this will not only save your hands from becoming sore but will also turn out a better end product.