"Where should the groomsmen hold their hands when they are standing at the altar?

This is a decision to be made by the Bride and Groom.  Either together in from of them or on the side, but never, ever in their pockets!

"What buttons do I button on my jacket?"

Well the rule of thumb with the men's jacket is as follows: Starting with the top button - it is Sometimes, Always and Never.  Which ever the groom decides is how the rest of the men should follow suit. 

Get to the Church on Time!

Too often I have heard people tell the Bride, "it is your day" and  "it is all about you" and most commonly said "they can't start without you".  This is true, that the wedding can't start without the bride, but do you want everyone to be upset with you.  Be respectful of others and other peoples time.  Being late on purpose is not a nice thing to do ever.  An organized person will make sure that they allow themselves enough time to "get to the church on time".

Consider ordering an extra boutonniere.

Some florist include an extra boutonniere, if they don't, make sure that you order one. They can break easily. In a pinch I have made a boutonniere by taking a flower from one of the bouquets. The grooms boutonniere can really take a beating with people hugging him.. Consider ordering an extra one for the groom.

Make sure that the person receiving the flowers has a list of what to sign for.

If you are having your flowers delivered somewhere other than where you will be, church, chapel, reception hall, make sure the person receiving them knows what you ordered.  How many bouquets, boutonneres, corsages and other. 

Do not let the guys pin on their own boutonnieres.

It is best if one person can be designated to pin on all of the boutonnieres, that way they will all look the same for the pictures.  The proper way to pin them on is from the back of the lapel, so that the pin does not actually show.

Be respectful of other people's time!

Be on time for appointments and especially for the rehearsal and the actual ceremony.  There is nothing worse than hearing someone tell the Bride, "don't worry if you are late, they can't start without you." That is true, they cannot start without the Bride, but the quality of the ceremony could change as people wait and get irritated and impatient.  It is a respect factor!