How do I be a good bridesmaid?

[RosesAndCrows]

A bit of background, my brother is getting married this winter and his fiancé asked me to be her bridesmaid. They've very kindly offered to pay for everything (dress, hair, flowers, shoes, makeup etc) and have generally been very easy going about more or less everything, SIL was quite firm on what she didn't want me in with regards to my dress but that's perfectly reasonable and I wouldn't have picked the things she definitely did not want simply out of personal preference so it's all fine. And things are still good, more or less everything that can be done this far in advance is done but I'm kind of worrying about the day itself. I can be very intolerant, stressing people annoy me, I'm totally out of my depth the second we get to showing any form of emotion that's not being majorly pissed off and can sometimes be an right b*tch without any effort or even conscious decision. I like my SIL and I want us to be able to remember the day for all the right reasons so what can I do to be good/helpful/considerate in the run up to and on the big day?

[AuntieStella]

Smile.

Do whatever she asks, unless it's totally impossible (so try not to fill your diary in the immediate run up with immovable important events). Find out if there is going to be a rehearsal and when, and any auxiliary events, such as family dinners the night before, or survivors' breakfast the day after.

Answer any texts/emails promptly, and put everything into your calendar straightaway.

Smile some more.

Be ready to do the standard things, like looking after small bridesmaids and being general dogsbody whilst dressing/primping.

Don't drink too much until safely at the reception.

Shagging the best man is only ever optional.

And keep smiling.

(vent here is you ever need to)

[areyoubeingserviced]

Totally agree with Auntie, .
Smile, smile and smile some more.
Don't take things personally.

[guest2013]

Don't get pregnant and steal her thunder
Joking!
Just enjoy yourself and be attentive without being under her feet on the day.
In the run up, always act interested, even if you're not! And offer to do as much as you can manage. Don't take on too much.