Slow, slow, slow.
Big cow-sized pile of butter in pan, on a low, low heat, wait for it to melt but not get hot, you don't want to fry the eggs. Crack in the eggs and start stirring, keep stirring, then stir some more, then stir a bit more, and then keep stirring. The eggs will eventually start to curdle, keep stirring, the aim to keep a smooth, veloute texture. Once they start to come together turn off the heat and keep stirring. The result shouldn't be too wet, it's not custard, but it also shouldn't be dry clumps of eggs. It should have an even texture, indeed not the curious alien sex gloop that serve in hotel breakfast buffets. Never eat the hot stuff in hotel buffets anyway, it's always odd. I usually make a giant cheese sandwich. It's like a mission for me, if it's going to cost $35, I'm going to construct a sandwich that really would cost that much. I start by taking the entire tray of cheese and work up from there.
Salt and pepper will do the trick. I sometimes go off-piste and add oregano and chopped tomato at the end. I normally support the addition of cheese to everything, but I don't think it adds much to good scambled eggs.
The butter makes everything better is a truism. If you've been in a proper kitchen you'll note two things: whereas you'd use a little pat of butter, proper chefs use butter in quantities that would make your arteries run like the A40 at rush hour in sympathy. The other thing is salt. They're not scared of salt. They're serious about seasoning.
You can go a bit crazy, of course, and turn your scramble into nasi goreng (which, Chez Asbestos, we call nasty orang utan). Toss in some cooked rice, ginger, shrimp paste, any meaty bits, kecap manis, tamarind, and chilli (and season it with MSG). It's one of the best and easiest meals to make.