Painting an existing Retaining Wall

Hi there. I've just joined and this is my first post ever! Yes, I am excited, but even more excited that I may get some advice on how to tackle the retaining walls and fences around my home.

So here's where I need some help. I'd like to paint the retaining wall in my backyard (1.72 metres at it's highest point, 23 metres across), and underneath the fence on the left side of my home (1.43 metres by 28 metres).

I believe the retaining walls around my home to be made from single treated pine and is not in the best of shape - for a 7 year young house, it has not weathered well. Some of the sleepers are already starting to split and my boys often try and pull the lose bits off (when they think I'm not looking of course). A lot of the sleepers have knots in them, and in a year or two, I might even be able to put my finger through a few of them!

So, I am going to give them a paint but I'm not sure where to begin.

Some of my concerns:
1. The sleepers that are splitting and starting the separate, do I try and nail them back in place, or pull them off?
2. How do I prepare the wall(s)?
3. Is there a recommended brand to use? How many coats should I apply? (I was thinking a coloured paint to help hide the imperfections)

Thanks so much in advance for your input!

Elisa

Please check out my photos: http://www.renovateforum.com/members...bums/backyard/