I tend to advocate the ‘cumming is good, but not cumming is so much better’ approach especially with the daddy dom type who tend towards the kind side of kink..
Keep it all positive. From a dom’s perspective giving you orgasms is often quite a power trip and watching you completely lose it as we make you cum is incredible, so for many it is a bit of a struggle to get their head around you wanting that to stop.
But straight out saying it, often in terms of ‘do you think we could try something?’ can quickly convince them that as great as watching you cum is, not letting you is so much hotter. The way you act when you’re insatiably horny, how you lose it, not just for seconds but all the time, the fact it brings your submissiveness to a new level. Once he tastes those fruits it’s a much easier sell.
So yes, the ‘try something’ line is a great starting point. And once that goes well there’s a few resources you can use. One is I’ve written a letter just for this scenario, which I now can’t find on Tumblr as the search is so crap now so here’s it reposted to my ‘blog in progress’:
The other resources as I mentioned in the last reply is that my entire back catalogue of kinky shit is now on edgingspace.bdsmlr.com so if you can encourage him to read that, get turned on by it, even play and pleasure him while he reads it, well, you my dear follower are monumentally fucked.
Just the way you want it.
Hope that helps,