How do you pay electricians?

[Literallynoideaatall]

This is such a silly question I know but I've never had any trades people do anything at mine or anything before I don't understand how you pay them, I have really bad social anxiety so I just want to know what to do
do you pay them cash when they're here? Or will I get a bill I can just pay by bank transfer?
if they're from a company then do I pay the company?
I know it's so stupid but having to talk to strangers is my worst nightmare I always make such a twat of myself!

PS I realise I've said tradesmen automatically (sorry!) but honestly, I've never had a female tradesperson do any work for me. I suppose I wouldn't want to go to random people's homes either from a safety POV, and sometimes if it's a small job, you only get one person turn up.

Usually you ask several companies to quote on the work and then choose based on their reputations and cost. DH and I have used one company over and over again so we don't bother with multiple quotes, we just ask them to do the job as we like the quality of their work. They will send us an invoice and it tells you when you need to pay by and how to pay including bank details. We pay by bank transfer as soon as we get the invoice. Last year they were so busy we had to chase them for the invoice for about three months.

I just ask them, as different people do it differently.
When they’ve finished I usually say “should I pay you now or will you send an invoice in the post?”.

Always get a receipt, however you pay.

I've had loads of different trades at mine recently as I am having lots of work done. I've asked them all to email an invoice and I then pay by bank transfer. I like to know exactly what they are quoting for in the first instance and then they send the invoice when completed. If they have to do more work they have emailed an amended quote. None has been difficult about it.