The thing that I found that the students needed the most help with is spelling and conjugation, so it isn't a bad idea to refresh your memory in order to best support the students.
When I first started helping in my class, the students wouldn't ask me for help when I was circling around the room. A strategy that I found to help with this is asking the students if you can see what they are working on. If you start the conversation they are more likely to ask you questions that they have or ask for your feedback on their work. I also found it useful to pay attention in class and follow along with what was being taught. It is important to know what you are talking about and paying attention to the class is a great way to refresh your memory.
It's helpful in mentoring Spanish classes to pay attention to the lesson and practice the IPA's with the students. This will let you answer questions better and feel more confident in your answers.
It helps the students with the language a lot more if you don't directly tell them the answer for verb/conjugations or specific words that they're looking for, but instead help them convey the message they want using words they already know, because language classes aren't about memorizing what different words mean or how they're conjugated but being able to communicate comfortably.