In reply to C Witter:
Some more serious ones...
(mostly mine refer to ice climbing but are probably applicable to most types of climbing)
- It's always steeper than it looks.
- It's always harder that it looks.
- It's always thinner that it looks (normally applies to routes described as 'good' early-season condition).
- Rule #1, wear a helmet.
- Rule #1, don't fall off.
- Rule #1, don't follow people up the same line.
- Head torches mandatory.
- Place screws in honour of every person who has fallen off ice climbing and can now no longer ice climb, even on easy ground.
- Slow is smooth smooth is fast (to quote blackhawk down).
- Every movement should be deliberate.
- Check the weather forecast.