Need advice on painting over rendering

[OM2]

We have cream rendering on the outside of our house.
I need to paint the back of the house where we've had an extension a few years ago.
I'm worried I might make a mess of painting over the rendering and wanted some advice.

This is what we have currently:

I'm thinking painting over the fine lines is asking from trouble - I'm thinking maybe some lines will get covered, while others won't and end up making it look a mess.

Any thoughts?

 

[opps]

The masonry paint may well fill those cracks.

 

[Nige F]

Apparently there is a silicone masonry paint for this job. Have a google.