This might sound like I’m a bit too nerdy about thing, but this at times can be very important to know and think about
Know from WHERE you buy it
Check the seller, are they likely to sell you a counterfeit (fake) product? This is a possibility online and in some parts of the world. If it sounds too good to be true, it most likely is.
Know from WHO you buy
That guy that sells it “very cheap JUST for you” in the back in a rusty maroon 1980’s Peugeot. Just do not. Stay away. Buy from a Seller that you trust, or like a large chain. Do some research. If it’s too good to be true, it’s most likely not true.
Know WHAT you buy
If you buy an american phone, and expect it to fully work in Europe/Asia you might be very disappointed later on we you realize that the 4G bands of it doesn’t work in Europe/Asia/etc. Do you homework before you buy it, like what hardware it got and so on. And with an american carrier phone, you will most likely NOT get updates if you are using it outside that American network. A Japanese phone is a big NO NO since there’s CDMA networks there, will be problems. So, read up on what you need. Read up on what you get. Ask around.
Learn what it’s called
Yes, learn just what name the phone got. So, you don’t go to a phone shop asking for “that new HTC phone”. Which will tell the seller that you don’t know (and perhaps don’t care), which means that they will try to sell you what they make the most on and not really what you want.
KNOW your consumer laws
This is at times VERY important, since the Seller at times doesn’t care very much of that. And, NO: a Seller in the EU can’t send a phone to repair over and over and over. It’s 2 times in Sweden and 3 times in the UK. If you got a brand new phone inside EU, and it got problems straight out of the box: take it back to Seller and don’t accept anything else than replacement with new. Don’t even use the phone if you see that it’s damaged when you unpack it, unpack it at the store/seller can sometimes be a good thing. “it’s not supposed to look that way, huh?”. HTC is warranty, a Seller got legal obligations around your purchase (at least under EU laws).
Know what sim card it takes
I know that this sounds a bit too simple, but if you get an HTC One M8 you can’t just pop out the sim card from your One M7 and expect that sim to fit in the M8. M7 uses micro-sim and M8 uses nano-sim. Like you can’t use a sim from the M7 in an older phone, since that phone uses a mini-sim