if I were you
Advice
We often use the structure If I were you … to give advice. British English has should or would in the main clause; American English would.
- I wouldn’t/shouldn’t worry if I were you.
- If I were you, I’d get that car serviced.
If I was you is also possible. Some people consider it incorrect (see here).
I should/would …
Sometimes we leave out If I were you, and just use I should … (British English) or I would … to give advice.
- I shouldn’t worry.
- I would get that car serviced.
In this case, I should/would is similar to you should.