When we had the kitchen ceiling re-plastered in May, the builder left an almost complete bag of plaster behind. He left it outside but we spotted it and pulled it in before it got wet and, over the past couple of days, we have been using it to patch some of the larger holes left in the walls where we took the tiles off.
Purchasing a float (a large metal rectangle with a handle on the back) was a good plan and it turned out to be relatively easy. Some areas are better than others and I am certainly not ready to turn professional but it will be good enough for areas that will be hidden behind shelves and cupboards. Apart from using the proper tool, the other important trick seemed to be going for a relatively wet mix. I am sure it is possible to overdo it but plaster is good at adhering to itself and to walls so keeping it loose enough to smooth across the wall in a single fluid motion is helpful for a good finish.
Now we just have to wait for it to dry and then paint it to see just how good it has really come out.