Verbiage

Language is one of the most common ways we exclude people. Be aware of this.

Gendered Language

Ableist Language

Assume Everyone is Technical (But don't assume anyway!)

This is something that happens at tech events, especially to women. A woman is having a conversation. Someone says, "Oh, are you in marketing/sales/etc?" That's so insulting to someone who has spent just as many years building their career as a man. She is assumed to be non-technical because of her gender. Don't do this! At a technical event, not everyone will be technical, but go on the assumption that they are. A marketing person is not likely to be offended if you think they are a developer.

That said, don't assume anything about anyone! It's much easier to say "So what do you do?" It's a very easy question and the most natural opener at a professional event. Learn to ask instead of assuming.