"A tip about overtime...Don't do more than 2 overtime days in a month because they'll just tax you too much otherwise and it'll defeat the purpose of doing it!"
I lose count of the number of times I hear that said! It's simply not true! You only get taxed at the higher rate on what you earn over the threshold!
Say the threshold was £2000 and you earn £2100 by doing OT, you only get taxed at the higher rate on the £100 excess, not the whole lot. Do as much OT as possible, you'll never lose money!
On the other hand, you could limit it to 2 days a month and leave more for me!