This may seem obvious, but the most important person to impress at work is your line manager (your boss). S/he is the one who has the biggest influence on what work you do, what (if any) bonus you're entitled to, whether you're deserving of a pay rise, what training the organisation will finance for you and so on. Your line manager is also the gate-keeper to more senior members of the organisation and likely a person with numerous contacts within the organisation and/or across the industry.
The only way to impress your boss is to clearly understand what s/he expects from you, then deliver work that exceeds those expectations. This applies to more than just the output itself ( e.g. exceeding your sales target), but also the way you deliver the output (e.g. the relationships you build with your coworkers, the processes you put in place etc.).
