Mute your microphone unless you are speaking to the group. If your microphone is on, avoid sound playing in room, especially music
Disable your camera to minimize bandwidth requirements. If your camera is on avoid backgrounds with a lot of motion (ceiling fans, traffic out a window, etc.)
If you have a question type it into the chat box
Log in 30 minutes before the meeting starts if you need to test your set-up, otherwise log in 5-15 minutes before the meeting
Notify the host using chat if something is not working
To get the hosts attention try holding up a white card in front of your camera
Use a headset/earphones/ear buds if you have them. The echo cancellers will thank you
Use a headset with a microphone if you have one. Everyone will hear you much better than if you use the microphone built into your device or webcam