I found it particularly useful in if conditionals where I wanted to evaluate multiple expressions in the true or false clauses. For example, my implementation of for-each in MIT's Structure and Interpretation of Computer Programs Problem 2.23 goes as follows:

(define (for-each proc items)Here, if the list items is not empty, then I apply the procedure in proc to the first element in items and recall for-each, supplying it with the remaining elements in items.

(if (null? items)

#t

(begin (proc (car items))

(for-each proc (cdr items)))))

I learned about the begin procedure from this Stack Overflow discussion.