Why don’t you take extra classes in English if you want to become a tourist guide

My friend advised me to take extra classes in English only if I wanted to become a tourist guide.

My friend suggested I take extra classes in English if I wanted to become a tourist guide.

In my friend’s opinion, I will never become a tourist guide if I don’t take extra classes in English.

In my friend’s opinion, taking extra classes in English is necessary if I wanted to become a tourist guide.