Talking about your Age
Normally, you can simply translate the German word "mit" into the English word "with." But sometimes you can't. One example that I hear a lot is this: "With 18 I traveled to the United States".
This is an incorrect translation of "Mit 18 bin ich in die USA gereist." Instead, say "I traveled to the United States when I was 18" or "I traveled to the United States at the age of 18".
Here is a bit about my life story to illustrate a few other ways to talk about age:
My brother was 21 months old when I was born. No matter how old I got, he was always 21 months older than me. I was 3 years old and my brother was 5 years old when our little sister was born. Just after I turned 6, I started first grade. I stayed in the same school until I was 14 years old. My brother had been in high school since I was 12, and I soon joined him there. Shortly after I turned 16, I was finally taller than my brother, but he was still stronger than me. I started university when I was 18 and finished after my 22nd birthday. Just a few months ago I turned 31, while my brother was still 32. But since then he has turned 33. He's still 21 months older than me.
Prepositions are one of the hardest parts of learning English. Here are some more lessons where I show you some of the mistakes to avoid so you don't sound so German when speaking English:
More English Lessons for Germans