Space

With a full room going at once, nobody needs to fill every beat. If someone's taking a solo, drop down to a few long notes or stop for a bit.

Sounds

Look at what's already there before you pick an Instrument. If the room has two pianos, a bass or a string sound will add more than a third piano would. Long, held sounds like strings and choirs work well under a busy piano, while staccato sounds suit faster playing.

Range

Low notes get muddy quickly, so if someone's already playing bass, keep your left hand out of there. Two people playing in the same octave tend to get in each other's way too. Transpose is handy here, because you can move up without changing your hand position.

Chords

Seat cards show the chord each player is holding, which tells you what key the room is in if you're not sure. If the host has the Next chord indicator on, you can see the change coming before it happens. A Backing track gives everyone the same tempo and chords to lock onto.

Balance

If you can't hear yourself, it's tempting to play harder, but that's usually what makes a room too loud. Change your register or your sound instead. If one player is too loud for you, turn them down in their Player menu.

Timing

Playing over the internet always has a little delay, so you won't hear everyone exactly when they play it. Pick one player to follow, usually whoever's holding down the rhythm, and stay with them rather than trying to match everybody at once. If things start to drift, the simplest fix is for everyone to drop out and let one person bring the beat back in. Slower songs and long held notes hide the delay much better than fast runs do.