I’m with Mower, about 95% of my external threading is single point. I like going full depth to the end and then ramping out (I’m qwerky, it is my own little signature thing - I like the look) - can’t get that with a die. With single point you can fit the thread if you want, and I get a nice surface finish.
I don’t know why you are not getting a nice finish, the suggestions posted above are good, and basically describe what I do. The brazed carbide tooling should work fine (I used it for several years). I like the Mesa tool, which is very similar to the Nicole offer. It is true the tip pops off easily, but I have a good arrangement for retouching the edge (generally sharpen it up to 3 times). I also use the partial profile and full profile lay down inserts (3 little points), carbide - gives a very nice finish. I like the ~29 degree on the compound, I don’t think the number matters much, just slightly steeper than 30 degrees. Staight in threading is fine, lots of people seem to make this a hill to die on - not a big deal either way IMO.
Speed? It is good to go faster than the typical threading speed, but slow isn’t a problem. I do most of my threading on a small English machine and it allows speed change on the fly - I start out ~100rpm and as I approach the end of the thread (ie a shoulder or the ramp out), then I reduce the spindle speed to 30rpm. The results are great. One could do the same thing if they had a VFD drive (speed change while threading).
Threading is another of those competencies that improves as you work at it. Keep trying, you’ll get it.
