What do you think, and what tips do you have?
Assalam alaykum
You will be just fine especially in Warsaw which is now getting to ne more and more cosmopolitan, I would suggest you pay a visit first see how you get on, I think it is quite possible to buy halal food and there is a mosque.
As in every country there are idiots especially the football hooligan types , just stay away from them, but on the whole Poland is a very safe country compared with the rest of Europe.