BI was very excited because it was my first trip to Europe, so I was very exited about it.

Nothing hugely wrong with how you wrote it but it's generally considered bad to start a sentence with "because."

I really like to visit museums during my tripwhen I travel, so Warsaw was the perfect place for me.

I'm assuming you mean for both business trips and holidays so I changed trip to travel.

AEvery day after I got off work, I visited one or two museums every day.

MIt had many photos, goods and books aboutrelated to the two World Wars were there.

If you were just talking about books, about would be fine. But I changed it to related because you're also talking about photos and goods.

I was really blown away by a real plane and a real tanktank they had on display.

I highly recommend to visiting there, when you if you ever have an opportunity to visit Warsaw.