Seeing you want to move in any European country apart from the UK and Ireland, you should first learn the language of the country you want to move in (if you're already doing, great!). If it will be so much easier for eveything in your daily life here, don't except people to speak fluent English all the time with you (except maybe in the Nordic countries idk)

In France, for instance (I guess it kinda applies to most European countries too) it's weird to start a conversation out of nowhere to a random stranger, it's even seen as rather creepy if you're a male, so maybe avoid that. Instead we usually make friends in little social circles (school, university, job, hobby, friend from a friend), so you could start hanging out with your friend in Hamburg and see what happens next.