Presentations are like breath mints. Never turn down an opportunity to have one.

Polite society won't tell you when your breath reeks, they'll just offer you a breath mint, so never turn one down. Likewise, polite society won't force you to present your ideas, so a lot of interesting ideas remain undiscussed because people don't bring them forward.

Giving a talk does several beneficial things for me:

1. It forces me to go through some material thoroughly enough to present on it, so I end up exploring the interesting nooks and crannies of things.
2. I get to meet new people (super-useful in a new country ;)
3. It lets people know what I'm interested in, so people feed me more relevant information, like how they solved the same or similar problems.

Society benefits when people share what they're doing. So give a quick lightning talk on something. After you feel you've mastered the 5-minute talk, try giving a longer one. Just go for it, your user group will always support you.