A few things to help you make better sausages.

Keep the meat VERY cold, from begining to end.

SALT: Mixing the meat with salt extracts a part of the meat protein known as "myocin" this is like a glue that will hold your sausage together and give it a good texture. The meat you use should be from tough cut. The more active a muscle is the more myocin it contains.

Mix the salt/ meat (preferably by machine), for a minimum of 5 minutes.
As you mix it, it will begin to get "tacky", that's the myocin being extracted by the salt.
As far as spices, and other ingredients you would like to add AFTER the myocin is extracted, is totally up to you.

Have FUN,

Joe