Here are my best bits of advice (as someone who regularly performs smears on others!):
say if you've never had one done before as nurse / dr should try be be extra careful and fully explain procedure (although I'm careful with everyone, as you can never be too sure what people's experiences have been like before)
tell the nurse / dr if it is painful. Although smears are uncomfortable, they shouldn't be painful, and if they are, it is usually because of something the nurse / dr are doing which can be changed, ie doing it too fast or being a bit rough. Just say 'ow' and they should get the message!
Nurses tend to be a bit more practised at taking smears, so I'd always ask the practice nurse to do it. Or going to a family planning clinic is a good idea where we're used to seeing women's 'bits' all day every day, especially if you're a bit nervous. The recall system doesnt tend to be as good there though (letting you know when you're next due a smear etc) so make sure you always make a note of the year you went and what the result was, just in case.
Nutcracker, you should still always be prescribed your contraception regardless of whether you've had a smear or not. There are some very valid reasons why people do not attend for screening (which is optional in the first place) and its not the nurses place to be judgemental and with hold your contraception.