1. Get a stable connection at home, preferably. Coffee-shops and other public places have shared WiFi, so the more users they have, the less stable your connection will be.
2. Ensure that nobody else in your house is streaming or downloading anything. The reasons for this are the same as above.
3. Make sure you are hard-wired via Ethernet and not using a WiFi router. Ethernet is way more stable than WiFi.
4. Shut down all other bandwidth and processing sucks during class like Spotify, Dropbox, backups, etc. Yes... Spotify is a bandwidth-draining ninja.
Also, are you aware that you can join from mobile devices as well?
Don't be afraid to use it as an option if you're having issues with your computer or tablet!