Let us analyze the sentence:
Steve was advised to keep his head down before heading out to bat – This means staying focused and cautious.
For, while he had a head for batting – This indicates he had a natural aptitude or talent for batting.
He could only do so with a cool head on his shoulders – This phrase means remaining calm and composed under pressure.
Thus, the correct sequence of words to fill the blanks is:
\[
\text{(i) down, (ii) out, (iii) for, (iv) on}
\]
Final Answer:
\[
\boxed{\text{down, out, for, on}}
\]