In high school, you or your friends may have done a bit of tutoring. So maybe you think of tutors as being for people who need help, who are struggling. But, as in so many things, "tutor" means something different at Stanford.
Stanford isn't designed for you to do it all on your own. Study groups, TA office hours, academic coaching, and tutors are all considered an integral part of the learning process. Successful students draw on all the resources that are available to them, and tutoring is often part of taking your skills to the next level.
Lots of places!
VPTL (Vice Provost for Teaching and Learning) has two main types of tutors--subject tutors and language conversation partners.
But you'll also find tutors through student groups, such as those for math or physics. VPTL has compiled a lovely list for you. And don't forget to consult the community centers--many smaller organizations offer assistance.
Looking to take your writing or speaking to the next level? Consult the Hume Center for Writing and Speaking or the Technical Communication Program in the School of Engineering.
And if you just feel like you need to learn to use your time better, or get more out of the work you are doing, meet with an academic coach.