The second 改成 Secondly—列据“第一、第二”等等,要用序数词firstly,secondly,thirdly
"the salesperson" 这里如果是泛指一般的销售人员,应改成“a salesperson” 或 salespersons
do our best 改成 do his/her best 或their best,视主语单复数而定,另外do的前面习惯上应该加个and
for customers 改成 to customers 固定搭配 provide sth.to sb.