Don't forget that the teacher will be nervous, too!

Hi, some advice I would give to you as a Spanish learner myself is to decide what you want to learn at the first lesson. Tell your teacher what you want to learn. Go through the lesson they prepare for you. On your next lesson spend about the first half of the lesson time speaking using your new grammar/vocab or whatever you learned in that lesson. Sometimes it’s a good idea to decide on something you want to discuss so that you can put together your thoughts, look up words, write out sentences, form questions, etc. Then spend the other half of the lesson time learning the next lesson (either decided by you or by the teacher). It may take twice as long, but the speaking practice is invaluable. ¡Buena suerte!

I am not learning Spanish, but I've been using Italki for learning French (and English) for five months. I was an absolute beginner in French. Just like Spanish, French also has complicated conjugations and grammar. I think if you want to book your first lesson, find a teacher who focuses more on grammar (and speaking). When you've passed your first lesson, ask the teacher what are the next topic and tenses that he/she will teach you, and you should learn it by yourself before taking the next lesson. So you can get familiar with the topic.

Have google translate open to look up words that you don't know, and do not be afraid to make mistakes. Just speak and listen and muddle through. Having a conversation is a different skill than just knowing grammar and vocab, and your first time will probably be a bit rough, but you will see a huge improvement in speed and fluency of speaking and understanding even by your 5th lesson.

Hi David, once I wrote a notebook entry about the subject: https://www.italki.com/notebook/4183033/entry/961360

Hope you find it useful