Getting ready for my first on-air contact and feeling overwhelmed by all the Q-codes I'm hearing. Q-Codes (also called Q-Signals) are three letter combinations that begin with the letter Q that CW operators use in place of common phrases. Which ones should I memorize first? I keep hearing QRL, QTH, and QRT but want to make sure I understand them before I key up.

Also, when followed by a question mark, the Q-signal turns into a question. So QTH? means "what is your location?" while QTH means "my location is..." - is this correct?

You've got the question/statement concept exactly right! The most common usage for this Q-signal is to ask if a frequency is in use before beginning to call CQ or another station. Start with QRL? (is frequency busy?), QTH (location), QRT (going off air), and QSL (confirm/understood). These cover 90% of what you'll need for casual contacts.

Learning the most commonly used codes will help you become relaxed and confident about using them in your transmission. Listening to other radio operators and hearing how they use Q-Codes will also help increase your level of familiarity and proficiency. Don't stress about memorizing them all - they'll become natural with practice.

Just had my first QSO last week and found that most friendly OMs will explain codes if you ask. Keep in mind that you may hear these Q-codes when you're operating any of the voice modes or when talking with other hams at club meetings or hamfests. Even experienced hams use them in casual conversation!