No particular knowledge for Estonia, but you can be scammed more closer to home. The revised classifieds rules on here came following scam buyers in the Sutton Coldfield triangle
If you see signs that worry you then don’t go ahead
But it’s entirely possible that you have a genuine buyer that is just abroad
Estonia is part of the EU, so while we are still in transition that’s a little simpler for no border tariffs
Whether the items are legal in Estonia and can be imported is their problem, but it would become your problem with an upset buyer
Look into suitable international postage for different size, weight, insurance, tracking / signature and restrictions along with cost.(Read the fine print about how far the tracking goes and what signatures mean)
Are you happy with that portion of cost and the likelihood of a successful claim for loss or damage
(When Im doing my Del Boy eBay sales I decide on a case by case basis whether to offer overseas postage, and if so I prefer the eBay international depot as a go between - it makes the overall postage cost higher as I charge for UK delivery and eBay charge the buyer a top up for onward postage, the advantage for me is a successful arrival at the depot closes my responsibility)
There are scare stories on YouTube etc where it seems to be common in the US to film packing and opening parcels.
If you feel the need then film/photograph the items,the package and it’s weight.
Take note of both weights on your scales and the post office scales (they will be different)
Consider payment methods. PayPal is the default and unless you hand someone your password then the transaction is safe. Don’t evade transaction fees, follow any dispute process to the letter, make sure tracking info is correct. The worst that can happen is a dispute finds on their side (which is the most often) and that compensation doesn’t apply to the problem. The default result of a dispute can be changed.
If the money is a lot then decide how the risk balances for you, and don’t spend it all before everything is settled
The highest value overseas sale I’ve made was £600 to Spain, I used the eBay depot, insured but not to the full amount (as the fee leapt dramatically to the next level)
But I was selling something that cost me £6. If it was lost my compensation would still leave me in profit, if things went horribly wrong then I lost £6 plus postage
I ended up with a happy buyer and a full wallet