I would apply PVA, 2 parts water to 1 part PVA, just to be on the safe side. It'll really help if you can get someone to mix and clean the bucket while you get on with the plastering. I mixed it faily sloppy, and applyed a thin coat, had a quick cup of tea and applied a second coat. When that's done, immediately go over it, smoothing out any trowel marks, and go over the corners. Excess plaster should be scraped from the trowel onto the mortar board, which can be used to fill any holes that need it in later stages, rather than mix a new batch.This is so that the plaster is drying at the same rate, and will not show up when you come to smoothing it out. At this stage it doesn't have to be too smooth. Leave it for another while, feel the plaster, you will get to know with experience when it's ready, just don't let the plaster dry out too much, and then smooth it out. Use a brush to fling some water on the wall and apply the necessary pressure with the trowel to smooth the plaster. Make sure to get the corners right, but don't trowel in straight lines for this. Trowel in a curved sweeping type motion. Keep the trowel and buckets clean at all times. It takes a brave man to attempt his first plastering job, but you will feel that you've learned a useful skill and might even get requests from others (I did). All the best.