This might not be ten things. Let's see.
1. Get a foreign-exchange fee free credit card before you go.
2. Get all your financial house in order; if you have a house that you're keeping as a rental, remortgage it or sell it. In my experience it is *bloody hard* to get credit in a country you are not resident in!
3. Get an American Express card. Why? They are the only credit company that actually 'does' credit cards (VISA and MC just do the interchange; you don't go to VISA and directly apply for a card) in most countries - and they have a 'global transfer' program, meaning when you arrive in your new country you contact Amex in the new country, apply for a card and tell them you're doing a transfer (you don't have to close down the old card). Bang - instant credit in the new country, and the best thing is they say you've been a member since your earliest card in the first country!
4. While you can often/sometimes transfer your driving license abroad, your destination country's insurers might not take your driving *history*. Here in Canada I was treated as having a brand new license (which *technically* it was) after doing a license swap from the UK. $1500 or $1800 is what my first year here cost me, after my last in the UK being maybe GBP 300 - and for considerably less coverage.
5. Following on from 2, banks in your new country can't see your assets in your old country. Nor can they see your income. You will pretty much be treated as an 18 year old with no history - especially if, like me, you go self employed.
6. Exchange rates change. Seriously. By 15, 20% over a year or two. That rental property that was covering all your expenses? Not any more, it doesn't!
7. What is tax free in one place won't be in another. So while you can keep your old ISAs or TFSAs or whatever open - you won't be able to add to them - and you will probably have to pay tax on them in your new country.
8. Even if people speak the same language, Things Are Different. Especially for an introvert like me - either expect to take up an interest in Ice Hockey, or have some trouble relating. Y'can always talk about the weather, of course.
9. Might be obvious, but not only is humour different (You're all bastards.. no no it's a joke! Honestly!!), but.. everything is different. People's love or hate for government programs. Or governments. Honestly it really is better to not get into an argument unless you've really understood what the thing is. And even if you DO understand it better than the locals.. well.. probably not going to go down too well.
10. They don't sell Twiglets in Canada! UGH.
Ok well that worked out alright. Most of these are pretty unimportant, but number 10 is a bitch.