Snug The Girth Up Tight - or Not?

Reef really hard on the girth/cinch to tighten that saddle down right tight so it doesn't slip? 

Not!  How about doing one thing at a time first - like correctly positioning the saddle.  Snug yes, tight no.

Horses girthed too tightly get cinchy and dislike being saddled.  Really, it's like wearing a girdle three sizes too small.  How comfortable do you think you would be in that contraption?  So if you do tighten it too much, chances are the horse will either reach around and bite you, blow or go down on their knees.  So, a snug girth is the ticket, just about right in the horse's book anyhow.  Just remember to position the saddle properly and you shouldn't have girth problems.

The saddle should rest solidly and be level on the horse's back. Now, having said that, there are so many variations to horses backs, withers and rump and in saddles themselves, that this is sometimes a challenge.  Anyhow, assuming you can level the saddle on the horse's back, it should now be on/in the rider's center of balance - just behind the horse's natural balance point at a standstill. As the horse moves, engaging the hindquarters, his natural balance point (just behind and slightly above his elbow) moves back and under the rider as the horse rounds his back upward. Now horse, saddle and rider should be in balance.

Put your saddle pad or blanket over the withers and well forward. Now place the saddle over the withers and forward. Slide the saddle and pad backward until they settle into position, behind the withers and level on the back. This might seem like the saddle position is too far back. It is not.

The gullet of the saddle will be somewhat over the withers.  The saddle will be level and the back of the saddle won't be pressing into the loin area. The girth will not be immediately behind the elbow, but several inches behind the elbow instead.  Hmmm, that sure sounds odd if you were taught otherwise doesn't it?

If the saddle is too far forward, well over the withers, and the girth is directly behind the elbow, the movement of the horse's shoulders is restricted. Stride and lateral action are adversely affected. Properly positioned, the saddle will not need to be tightly cinched, because it will stay in position naturally with only a snug cinching.

Once the saddle is on board, check the pad or saddle blanket and lift it up into the gullet so that at least two fingers slide easily between the withers and the saddle. If you've properly positioned the saddle, you won't give your horse grief on his withers or loins.
You can spot problems from the ground if you just stand back and observe the tacked horse.