Safe rider tips

Before you ever get on a horse.
Walk around the horse in a complete circle and run your hands over the horses body. This may alert you to any problems the horse may have. An example would be a bur stuck to his flank or leg. Another example would be a cut or scrape that had gone unnoticed. Generally your just looking for any potential problems.
Next be sure the saddle has been properly tightened
 

I once had the displeasure of a saddle coming undone while I was galloping a very naughty horse with a very hard mouth. For about 30 miserable seconds I was underneath the horse in a full gallop. I was very lucky not to sustain any serious head or leg injuries.
Next be sure the Bit is correctly placed in the horses mouth.
The Bit needs to rest in the horses mouth where there is a spot with no teeth. Run your hand lightly along the gum of your horse. You can feel the spot where there are no teeth.



Most hoses will open their mouths when you stick a finger on this spot.
The bridle can be adjusted for your horse, so that the Bit always lands in the right spot.

When you mount your horse and get comfortable.
Be sure that only the toe of your riding boot is in the stirrups. There's nothing worse then falling off a horse and being dragged around the paddock because your foot got caught. Just putting your toe in the stirrup will prevent this.
Wear a helmet and enjoy your ride!