Prepping render before painting is vital, and it is important to understand the process. Be it filling imperfections, patching the render, cleaning, and of course, the painting.

The best filler available is probably Toupret. You can find a full review by following this link - https://www.thedecoratorsforum.com/to...

There are a couple of different masonry paints you should look out for.

Wethertex masonry paint – https://www.thedecoratorsforum.com/we...
Emperor Paints masonry paint - https://www.thedecoratorsforum.com/em...