Here, have six awful advices:
1. Set the bar high... and then lower it. So only the better teams continue competing, but the diferences are so small then that basically everytime it´s two or three second places.
2. Explain the rules of the game... and then forget them. You said 10 minutes? Let´s give them 15. Said no cheating? Politely turn your back to everything. Said no whispering right answers? Do it yourself and openly. Also give advice on the easiest questions.
3. Ban the use of mobile phones... and don´t pay attention to them. Ever.
4. Make the picture questions related to one country... let that country be Russia. So only older people will get it. Perfect.
5. Make the music round the most interesting... by letting the local students sing. So if you don´t know the song you cannot guess the singer by his voice. And continue to support their effort even they sing only "okay".
And finally 6. Set the day... and change it in middle of summer holiday. So everybody is confused as sh*t. Personally today is Friday for me... because yestersday was Trivia night... and in reality it´s so long till weekend .
.. ugh.