When I first went self employed about 36 years ago, I seriously lacked self confidence. I had been made redundant and hadn't got a clue how to be self employed or how much to charge etc. As a result I undercharged but still felt as if I was charging too much. So when customers asked how much they owed me I would say things like "I'm afraid that's £200" which left the door wide open for them to ask me for a discount. I eventually learned that by saying very confidently "It's £200" it left no option for the customer to ask for a discount, they just paid. That boosted my confidence no end.