Of course it's easier said then done.
In fact, I don't like the question "how to register the right domains?"
Instead, it should be: "how/where to acquire the right domains"
Because you know the deal on regfee domains. The golden nuggets were picked long ago, they aren't waiting for you...
In fact, listing the domains on the marketplaces like Sedo is not going to get you so many more eyeballs. Because there are millions of domains listed. Unless somebody is looking for your domain in particular, what are the odds it will be found.
That's why you must own domains that end users will be looking for.
Back to square one.