Let's make this simple. Hopefully newbies and lurkers will find everything they need here (or at least a few helpful things!). I honestly could have used a post like this back when I first started planning, so this is merely meant to be convenient and helpful! Knotties, please feel free to chime in, add things, correct any of my errors, etc!
Who should I ask to be a bridesmaid?
Your nearest and dearest; the people who mean the very most in the world to you that you can't imagine not having next to you on your big day. Here's something Knotties like to ask to help make up your mind: if you had to call someone to help you bury a body at 3am, who would you call?
When should I ask?
Less than a year before your wedding date. If you have over a year to go, WAIT. Relationships change and shit happens. A lot of brides who ask too soon end up regretting their choices later.
My FI has 5 groomsman but I only have 4 bridesmaids. Should I ask another person?
No. Refer back to "who should I ask?" Sides do not have to be even, so you should not ask someone just for this purpose.
How do I go about picking their dress?
Very first step: ask each BM-- individually and privately-- what her budget is for the dress. Stay within that budget, whether you want them all in the same dress, in a variety of dresses, or let them pick their own. Their budget is very important!
Should they pay for their hair and make-up?
Only if it's OPTIONAL. If you're requiring them to get their hair and make-up done by a pro, then you need to pay for this yourself.
What are the BM duties?
To show up on time for the ceremony in the appropriate dress and smile for pictures. The end. They do NOT owe you anything more than that. They are not required to help with crafts, DIY, set-up, or anything else wedding related. If they offer, great, and if they haven't offered but you would like their help then ask. But don't get upset if they would rather not help. This is your wedding, not theirs. They are not required to host parties for you, such as a bridal shower or bachelorette party. If they offer, great!
Should I demote my MOH/ kick someone out of the bridal party?
This is a friendship-ending move. If you're prepared to end the friendship, then go ahead. But make sure it's for valid reasons and not something like getting upset that they're not as obsessed with your wedding as you are. No one is going to care about your wedding as much as you and your FI.
What should I give them for their BM gifts?
Shop for each of your BMs individually, as if it were her birthday. Get something that's tailored to her own individual interests or hobbies, but try to spend roughly the same amount on each person. Giving them something that's meant to be worn for the wedding is not a gift.
Should I seat the bridal party at the head table, or with their SOs?
Please set them with their SOs. You could do a sweetheart table for just you and your FI and the bridal party can sit with the rest of the guests, or you can do a kings table to include bride and groom, bridal party, and all of bridal party's SOs. It is considered very rude to expect people to celebrate your relationship but then bash their relationships by not letting them sit with their SO.
My BM is single but wants to bring someone to my wedding. Should I let her?
Yes. As a common courtesy to someone who is taking time, money, and effort to celebrate your wedding with you, please allow everyone in the bridal party a +1 regardless of their relationship status.
My BM skipped my E party/bridal shower/bachelorette party!
This is totally fine. (Refer back to BM duties). No one is required to attend these pre-wedding events. Everyone has their own life and their own stuff going on, so don't get offended and upset if someone can't make it to a party. They do not owe you an excuse, and it is not up to you to deem whether or not a given excuse is acceptable. Don't waste time getting upset about something this silly, and don't kick them out of the bridal party for this!
That's about all I can think of. Thanks, TK, for teaching me a lot of valuable stuff! Knotties, have I forgotten anything important?
*ETA: picking the dress, and hair and make-up