Stamps for envelopes

First, you can use whatever stamps you want. We opted for ones with flowers on them.

Second, take a completed invitation to the post office. They will weigh it and let you know how much postage you'll need.

I don't know about your envelopes, but just use any stamp you want. I used the ones they handed me at the grocery store.

Take a full invite to the post office and have them price them for you with whatever extra services you need, like hand canceling. Mine were .93 cents so two lovely quilled heart stamps are what I used. Haven't gotten a single one back.

These were my stamps, ordered from the post office online. They looked amazing on our dark grey envelopes. Plus, the two hearts together seemed fitting for a wedding invite. :-P

I agree with @Kate.

We used Star Trek stamps for our RSVPs...

Whatever you do, take one to the post office first and get it weighed!

I just did the forever flag stamps, I really didn't care what stamps we used.

I don't think there is really any etiquette involved, but I wouldn't bother. Go to USPS.com and look at the stamps; there are fabulous ones.

You don't have to have custom stamps, but speaking from experience, I loved mine. I went through Zazzle and got them during the best sale I could find on stamps after waiting 6 months to pull the trigger.

I mis-weighed my envelopes though (forgot to add the belly band and invite mat) and needed to purchase one extra stamp for all of mine, which ruined everything for me because they were lame birds that didn't match my colors lol.

I used vintage stamps but photo stamps are so cool and a beautiful touch. My A7 envelope with a thick card stock invitation and details cost .70cents to mail

I bought the love sky writing forever stamps at the post office. I didn't want to pay extra for any custom made stamps; ultimately they'll end up in the trash.