It helps to reframe the issue. "Selling" yourself is distasteful for many, because it smacks not only of loudness & brashness, but of straight up lying.
Look at this instead as a problem of knowledge distribution. In the extreme case, you do absolutely brilliant work, but tell nobody - how would people in charge of promotions/funding know you did that work?
That's the first step. You need to let people know your work exists, otherwise they really can't reward/recognize it. (Or really, in the extreme, you need to let them know you exist as the very first precondition).
The next step is the fact that you are the person who has likely spent by far the most time on the problem. You intuitively understand why this is an incredibly important problem, and why the solution is really, really good. I guarantee you that the people around you don't. How would they? They've spent much less time on it than you have.
And so part 2 becomes educating others on the problem and on the solution.
So, no, you don't "sell" yourself. You publicize and educate. It's still incredibly hard, but it captures the core of what's actually necessary much better. There's no need to be loud & brash, to paint everything in the brightest possible colors, but there's a need to communicate.
If Einstein hadn't written a paper on special relativity, he would (obviously) not have been recognized for it. And if he hand't communicated his insights very clearly and crisply, he wouldn't have been recognized, either - several people before him spelled out some of the insights, but in a much less clear manner.
So, don't "sell", just let people clearly know what you do,and why you do it. Looking at it from that angle has helped me tremendously getting over the "selling is gauche" issue.