Not personality transplants. Just reps.
Write weekly. Doesn't matter where—internal docs, blog posts nobody reads, detailed comments on PRs. The rep is: explain something technical to someone who doesn't have your context. Then get feedback (or notice when people misunderstand, which is feedback).
Toastmasters is cliché but works if you actually go. Lower friction alternative: record yourself explaining a concept for 3 minutes, watch it back, cringe, iterate.
Start with maintenance, not expansion. Message one person you already know professionally every two weeks—share an article relevant to their work, congratulate them on something, ask a genuine question. No agenda. The muscle is staying loosely connected without it feeling transactional.
For expansion: comment thoughtfully on LinkedIn posts from people in your target field. Not "Great post!" but actual substance. Some will respond. Some become conversations.
This one's harder to rep deliberately. Closest approximation: put your work in front of critical audiences regularly. Code reviews where the reviewer is harsh. Posting projects publicly for feedback. Open source contributions where maintainers will nitpick.
The goal isn't to enjoy criticism—it's to stop having a physiological panic response to it. Exposure therapy, basically.
Write down your accomplishments weekly. Literally a running doc. Most people can't articulate their impact because they never logged it.
Then practice asking: in low-stakes contexts first (asking for a different table at a restaurant, returning something at a store, requesting schedule changes). The rep is making requests and surviving the discomfort.
Frame every request as: what's in it for them? Practice this framing in writing first—emails, Slack messages, proposals.
"I want X" becomes "X would help us achieve Y, which you care about because Z." Eventually this becomes reflexive.
All of these are exposure + reflection, done consistently at low intensity. Not personality transplants. Just reps. The gap between "minimum viable social skills" and "natural extrovert" is smaller than you think, and entirely closeable with deliberate practice.