I anticipate that you will get a variety of recommendations on your question, DeanoZ. Here are my suggestions, based on my personal experience only:
1) I believe it is always best to start out conservatively with your calling. Using basic yelps and clucks (and in combination with other natural turkey sounds--wing-noise imitations, ground-scratching imitations) is generally a wise decision in most situations. In early morning "roosted gobbler" situations, it is important not to get too carried away with your calling, and often a single series of three or four "tree yelps" is all you want to offer up to a bird. Yes, turkeys "cackle" when they fly down sometimes, but in many cases, they do not. It is a difficult call for the average turkey caller to do well, and it can easily raise an old wary gobbler's suspicions if done poorly or in the wrong circumstances. The "tree call" is a much safer bet. In any event, calling too much to a roosted gobbler is rarely a wise move.
2) Once a gobbler is on the ground, you have a wider variety of calls that you might use, with yelping, clucking, and cutting being included in that selection. A basic axiom in turkey calling is that you can't take back a call once you have delivered it....therefore it is often best to call conservatively at first and then work towards more aggressive calling. When a gobbler hits the ground from his roost, the best initial calling choice is often just another series of yelps (wings, scratching, per above). I usually reserve the use of cutting, which to me is a more aggressive call, until after I am convinced a gobbler is not going to come to conservative calling...yelps, clucks, maybe some purring. Cutting--- quick, randomly-spaced clucking---and yelp/cutt combinations can be deadly and I like to use those calls, but they must be used with discretion.
My basic suggestion is always start conservatively and then work towards more aggressive stuff, depending on how a bird responds.