There are a plethora of educational websites that are doing very well in connecting students with tutors. Here are a few with some information regarding how to get going in them.
1. Tutorindia - Tutor registration is free. You need to update your profile once every 6 months to ensure that it stays on top of search lists. The website will offer you a mechanism to get in touch with students who are looking for online/offline help. Conversely a student can also directly contact you by looking at your profile. The site is not responsible for deciding or passing fees between student and tutor though.
This site is good for putting your name out there since it gets a lot of visits from students from India and abroad.
2. Prestoexperts - Registration is free but you need to make profile worthy and attractive enough to get it approved under your desired subject heading. Approval may take upto a week at times. Once approved you can bid for various public requests made by students, and students can directly mail or chat with you via prestoexperts messenger. For whatever work the students want, you need to discuss and fix a price which the student (client) will confirm. This money is then transferred from the student to website. When you complete the work and send an invoice to the student, the money is transferred from the website to your account. (This protects both students and tutors from fraud). The website sends money to you via cheque or Paypal at the end of every month as long as you have earned more than $50. In lieu of the services provided, the website deducts 30% of what the client pays you (for jobs under $500).
3. Teacheron - This is a branch of tutorindia that is based purely on online teaching. Furthermore, it follows a pattern similar to prestoexperts when it comes to client student interaction and payment. Only difference is that they deduct only 15% of your earnings.
4. Eduwizards - Registration is free and you need to upload your CV along with your qualifying degree in order for your profile to be accepted. You first need to complete few hours of "Tutor travels to student's home" type of classes in order to get enough reviews for your profile to be accepted for online classes. You decide your hourly/monthly fees but the website again deducts a percentage (different percentage for different modes of teaching) before giving it to you at the end of the month.
5. Buddyschool - Registering and activating your profile to make it visible to students costs $1 pm, $5 per half year, $10 per year. Once in, you can set your hourly rates and set your availability schedule. The student pays the money to website on booking a session with you however that money is transferred to you via paypal only 24 hours post completion of your session.
There are many more such portal existing and flourishing today like Vedantu, Mystudycart, Tutorville, Tutorvista, etc. The best way to go about it is to sign up in as many such websites (the ones with free registration) as possible to increase your visibility. This will automatically lead to new educational portals calling you on their own to join up their websites as well.