How do I waterproof my render?

Step 1: Wet the wall with water. Step 2: Prime the wet wall with a mixture, consisting of, 4 in 1, which has been diluted in the ratio of 1:1 with water and added to cement until a creamy consistancy has been reached. Step 3: Render on two 6mm coats of cement and sand, which has been mixed in the proportions of, 1 part cement and 2 parts dry sharp sand by volume, and has been mixed with a liquor consisting of 1 part 4 in 1, and 1 part water. Step 4: This mixture is then trowled onto the wet or tacky primer which is protected from premature drying, by covering with polythene sheet.