Hello everyone! I am just getting started in postcrossing and would love some advice regarding how many stamps to have on hand and what values I should get? I would like to make a purchase on the USPS website soon, unless there is a better source?
Thank you so much for your time!
It depends on how much you care about what stamps to put on the postcard. If your main concern is to maximize space, get the international forever stamps, since you will only need one per postcard.
If you also want to match other people’s preference for a variety of stamps, you can mix and match the other values.
For example:
One $1 stamp + one additional ounce stamp (.20)
Two forevers and a ten cent stamp
A two ounce stamp + 2 additional ounce stamps + one .05 stamp
Three domestic postcard stamps + one ten cent stamp + one 2 cent stamp
Also note that the stamp prices will go up after August so you’ll have to adjust for the $1.30 rate then.
Edit to add: If you have in your preferences to also send within the country, you will only need a domestic postcard stamp which is also considered a “forever”. It’s currently 36 cents, but will also go up after August to 40 cents.
I recommend that you get First Class Forever stamps (55 cents each) and 10 cent stamps (the red pears). Then you can use 2 Forever stamps + one 10 cent stamp to equal the current international postcard rate.
I personally like to have a wide variety of stamps on hand, because I know that I will use them eventually. I buy stamps online through USPS’s website or through the USPS ebay store (they used to let you used ebay coupons on stamps! and accumulate ebay bucks!). You can buy stamps off ebay for below face, but they’re usually older designs that I don’t care for, plus I don’t like to have to use glue.
My USPS order has always been picked accurately. The only thing I don’t like is that each sheet comes sealed in a plastic sheath and with a cardboard backing. I feel that the amount of packaging is a bit excessive.
I think if you buy stamps at your local post office, they will sell you partial sheets. Your local post office may have airmail stickers as well. It’s purely for decorative purposes, but I like to use those stickers. Only one local office has them.
I don’t do Postcrossing domestically, so I don’t keep the domestic postcard rate on hand. I do buy the round Global Forever Stamps for when I go on vacation and mail out cards.
Late last week, the USPS submitted a rate increase request. I’m not sure whether it’s guaranteed to be approved, but I saw that if it does get approved, it’ll go into effect in late August 2021. So keep that in mind.
Just a heads up - USPS is increasing prices starting August 29th so the combination of 2 Forever stamps + one 10cent stamp will not be enough.
https://about.usps.com/newsroom/national-releases/2021/0528-usps-proceeds-with-request-for-postal-rate-change.htm
I like to have a variety of stamps at hand and just add the values up to the correct rate depending on how much space I have left on the postcard to place all stamps.
Agreed! At the very least, the cardboard pieces are conveniently sized for stabilizing envelopes, should you ever want to mail something that should not be bent. 
I tend to save a few of them for this purpose!
Most of the advice I’d offer has already been stated, but I would emphasize a couple of things, and add another thought or two.
The domestic postcard rate is lower than the international one, and there are specific stamps for that. Currently, the first class letter rate is $0.55 and the postcard rate is $0.36. These will increase in August.
Many U.S Stamps (and likely most of the ones you’ll be using) are currently issued without a denomination (money value) printed on them. Instead they have the word “Forever” printed on them. “Forever” stamps are always good for the current first class rate, regardless if the rate goes up. Part of which is to say that you’ll want to accumulate a bunch of these before the rate increase in August. More on the rate increase can be found here: https://about.usps.com/newsroom/national-releases/2021/0528-usps-proceeds-with-request-for-postal-rate-change.htm
Consider the size and orientation of the stamp. Postcards are small; smaller stamps fit better, as do vertically oriented ones. This is not to say that you cannot use larger or horizontally oriented stamps; only that it may present more of a challenge to find a combination of stamps that will fit. All of which is to say it is noice to have a variety on hand.
Domestically I just use the currently issued postcard stamp, as I feel like other Americans all have access to the same stamps I do. Internationally, I usually use two domestic first class rate (2x.55=1.10) plus additional postage to hit the $1.20 mark. For additional postage, I purchase older unused stamps from eBay in a variety of denominations. If you search and are patient you can usually find them at close to cost.
Even if they do not mention stamps in their profile, people appreciate them. If you can find stamps that suit their interests thematically (the postcrosser who is interested in birds not only receives a postcard of a bird, but with various bird stamps, for example) it shows a little extra effort on your part, and is always appreciated. Don’t forget you are sending a gift to a stranger; make it as nice as you can! This will pay you back in the long run.
In case you make some penpals and start sending letters: note that the international current first class rate of $1.20 is only good for one ounce (except up to two ounces to Canada and Mexico) The rate goes up after the first ounce for each additional ounce, and it varies by destination.
Hope this helps!
@eta55 and @AndAllThatJazz covered all perspectives about using the USPS for stamp purchases. I have used that site for many years. With Official cards that go by themselves, I usually use two Forever commemoratives plus the $0.10 small stamp. With In-Envelope trades, however, besides the two $0.55 commemoratives, I usually add an older issue US Commemorative. The latter can be anything between $0.10-$0.15. Older US commemoratives are plentiful and often available at face value.
Whatever you do, make sure you only buy your stamps from USPS, either in person at the PO, by mail from USPS.com, or from the official USPS Ebay store.
Do NOT buy the deeply discounted stamps on EBay, Etsy, Amazon, etc., THEY ARE FAKE. I just found out that stamps I paid $50 for are fakes, the seller is long gone, I’ll never get my money back, and it’s a felony to knowingly use them.
I was going to offer the same advice- because you saved me last week!
You were RIGHT! I was able to get a full refund from eBay eventually.
Now I have a bunch of pretty stickers.
What a great post thank you.
How did you discover the stamps were fake?
There was another thread about how the deeply discounted stamps were almost certainly fake, and a suggestion to google it. So I did, and found several articles in the very reputable Linn’s Stamp News that described the fake stamps. I compared that with mine, and that’s how I found out they were fake. 
USPS is a great source to start. I usually buy stamps through eBay. You can find some pretty decently discounted stamps there.
As far as how many to have on hand, that depends on what you want to do. Are you only on the Official website or are you swapping in the forum, too. How often do you plan to swap? I generally keep several hundred dollars worth in stock, but I also send an upwards of 200 cards a month.