All excellent advice Youngmic. Here is another prop saving tip that was passed on to me by the operator of a fleet of GA aircraft that operates into many unpaved strips.
Before starting the engine select full coarse on the prop and be careful not to let the engine rev much on start up. With practice you can start without exceeding 1,000 revs. When you want to move off slowly increase the revs till the aircraft is rolling. You will notice that with full coarse selected the aircraft will move off 200 to 300 RPM less than with full fine selected. This achieves 2 things. First it is less inclined to suck rocks into the prop arc and secondly when the odd one does come through the slower moving prop incurs considerably less damage.
The rest is common sense. Many bush strips have a concrete pad for the flying doctor . Use it for your run ups. If one is not available do the mag checks at a fast taxi. On take off start the roll full coarse and once past the speed of a fast jog go to full fine (not TOO fast) and bring up full power. If you forget to go full fine the aircraft will tell you. It wont go any faster than 15 to 20 knots.
If the strip is a real bad one(Light bauxite stones or just graded strips are bad. Ones not touched since the last rain are better as the dry mud glues the stones down to some degree) consider not doing the mag check. What's more dangerous? The unlikely possibility of having to fly on one mag or the high chance of picking up a stone and inflicting unknown damage on the prop. I know this sounds a little complicated when you read it but in practice it is quite simple to do. Once we adopted this method prop damage was greatly reduced and I can't remember when we last had a bad rock chunk taken out of our prop.