I like the approach that the AUCTeX and/or CDLaTeX modes in emacs take: if I want Greek letters or math symbols, I hit the backtick, then the mnemonic or binding for the Greek symbol/operator I want. I know you can’t extend this to Twitter or something, but I would never want to anyway.
(
https://ftp.gnu.org/gnu/auctex/11.88-extra/tex-ref.pdf)