I thought that brickwork was tricky. Rendering was worse! I used a weak sand & cement mix with Rein fibre added to bond the mix.
The render was applied in stages. In all it took me two days to get the finish I wanted.
Once this coat had been applied I sponged the whole thing down which provided a reasoanbly smooth finish.
As the render was drying I sanded the wals down several times with wet&dry paper. A good plasterer would have finsihed the whole job maybe ten times quicker than I did, but in the end I got there. The cover came in useful here to protect the render from rain and sunshine.