Cheer-leading
A lot of people bring friends and family to the tribunal to support them.
This is an excellent idea. Tribunals are stressful, difficult and not the the sort of thing you should do alone unless you have to. Just knowing that there is someone there to give some emotional support can make things much easier.
Tribunals almost always have a row of chairs behind the parties for people to sit on. Most hearings are public. Even if yours is not, the tribunal is unlikely to object to people you know attending if you want them to.
The respondent will often have quite a few people with them too. The convention is that each side’s supporters sit directly behind the party they are connected with. This saves embarrassment on all sides and allows everyone to whisper about how things are going.
The advice about not making faces applies to observers as well as participants. Overt expressions of support will go down badly with the tribunal. In particular, hand gestures (of any sort) should be refrained from.
You know your friends and family best, but it might be worth reminding them of this before you go in.