You'll spit and slobber fora while until you get used to it... I actually say, "welp" or "yelp", without using my voice, just the air. Helps to get the jaw drop that really enhances the sound. Clucks " tutt". Cuts "tut tut tutt ttutt tuuutt tutt tutt" Cackles are similar, just not as long, and a little different emotion. For purrs, try to roll your throat, like gargleing water, and do that over the call, will take a lot of practice to get it under control.

Good Luck.