Be aware. Select committees aren't the sedate affairs they used to be since their members became elected rather than selected, and they turned to scrutinising business rather than government. George Pascoe-Watson, a partner at Portland Communications and a former Sun political editor, says: 'It's essential to know how to handle a committee well to avoid damaging your reputation and that of your business.'
Understand the context. 'You need to know whether you are being invited to appear as an expert witness or to be given a public flogging,' says Pascoe-Watson. In some inquiries, it could be a bit of both, but it makes a big difference to how MPs will treat you.
Do your homework. Swot up on the committee members. Ask the committee clerk for the likely line of questioning and even approach committee members to find out why you've been invited. 'The key thing is to know your stuff and particularly to have a grasp of the figures, as that's where people trip up,' says Julia Fea of parliamentary training consultancy Klibreck.
Choose your message. In Parliament's video on the subject, Andrew Tyrie, chair of the Treasury select committee, says: 'A good witness is someone who comes knowing what it is he wants to say, says it, and then when he's asked questions, answers them directly and with precision.' Think what single message you'd like the committee to remember from you.
Rehearse. Practice makes perfect, so assemble a room full of your own committee members and let them fire away. 'No actor would go on stage without rehearsing and it's essential you do,' says Fea. 'Anticipate the questions you could be asked in a worst-case scenario.'
Assume the right attitude. Your demeanour should be that you're working with the committee, not against it,' says Fea. 'Show the committee respect, even if you think the question's stupid. Imagine you're the host at an event where the audience can ask you questions.'
Don't be evasive. If you can't give an answer now, tell them you'll look into it.
Remember it's public. Your people, shareholders and other stakeholders will be watching. 'If you put in a poor performance it can have a big impact on the confidence of your colleagues,' says Pascoe-Watson.
Don't be intimidated. Be open but don't let the committee bully you into disclosures you'll regret. 'They will make use of parliamentary privilege to ask you some very blunt and sometimes rude questions,' says Pascoe-Watson. The MPs may be hoping to provoke you - or simply playing to the gallery.
Do say: 'Thanks for the opportunity to appear before this committee and I will do my best to help you.'
Don't say: 'Give me strength. I've been asked some pretty imbecilic things, but that takes the biscuit.'