You're going to have expenses, and it's best to understand who's going to cover these before you go. If your work is sending you, they should be covering the full cost of the conference and airfare. Some jobs might have you sign a contract before you go stating you're staying with the company for 1 more year or you'll need to reimburse them (this is quite standard I've found).
Some companies have travel policies (see below) and have specific amounts for each of the below categories.
Some items you will want to consider, and consider who's paying for them:
- Travel to and from the airport. Are you taking a taxi or parking?
- If you are driving, do you get reimbursed for mileage?
- Meals - you need to eat 3 times a day.
- Wage - are you getting paid while you're at the conference? Do they expect you to work as well? Is your boss expecting any documentation, writeups, reviews etc. to be produced from your conference? ***On this one, I'd recommend actually hosting a meeting with people who would be impacted from this talk, about what you learned, strategies going forward, any new best practices etc. Share the knowledge you learned even if they don't ask you to. Be proactive.
- Travel / Health insurance - do you need it?
- Who is booking the flight / hotel? Some companies have a Corporate Travel agency.
- Are you using your Credit Card and getting Reimbursed? Do you have a high enough credit limit? If you're paying for everything yourself then submitting expense forms, you might want to consider getting $$ before leaving to at least cover the cost of the airfare and hotel so you're not carrying a balance on your credit card.
All in all, conferences are draining for many a software developer (In my experience). Take notes, listen, meet people, and enjoy yourself. Take what you learn while you're there, and apply it to your career. Don't try to implement everything as you'll burn out. Take the best points you've learned, find out how to employ them in your career and with your team, and just do it.