Most graduate schools require at least 14 hours of volunteer experience in the field of SLP (and/or audiology). Often the SLP you volunteer with will be the one you'll ask to write you a clinical letter of reference. Here's how to make a good first impression and maximize your experience.
Okay, so I'm not the best poster-child for this point, but (I'm slowly learning) punctuality is extremely important! It shows that you care and that you're invested in your experience. Because you're not getting paid, sometimes it can be hard to show up on time but experience is a better reward than being paid.
Every institution/business has their own dress code and it's important to know before you arrive. If you don't feel comfortable asking your supervisor the dress code beforehand, I would recommend dressing business casual: a good middle ground.
Make sure you're ready for each volunteer session; whether you need to organize paperwork, research a specific case or assessment method or prepare therapy materials.
This is your opportunity to learn firsthand if SLP is a career that you are interested in. When you shadow an SLP, make a note of questions that you can ask throughout the process. Often there will be an opportunity to ask questions and it's your responsibility to learn all that you can about the profession.
Don't forget to document the volunteer hours you are putting in. Make a note of the dates and hours you volunteered for. This is beneficial because you need to include the hours you volunteered for in your applications and when you ask your SLP supervisor for a letter of recommendation, you can report your hours to them.
Bonus Tip: Don't just do the minimum of 14 hours. In order to build a meaningful relationship with your supervisor, it's important to show that you are willing to go above and beyond.