Know your process: In whatever industry you are working, your best tool will always be the complete knowledge of the process. If you are conversant with the ins and outs of your process, you can always maintain it well.
Know your equipment: The thorough know-how of the equipment and their specific maintenance requirements is also a must. If possible, keep a set of drawings, list of spares and list of suppliers along with lead time. All this comes handy during breakdowns.
Know your people: All the fingers are not the same. Same is applicable to people. Each one of us is specifically talented in different areas. Identify the strengths of your team and utilize them effectively.
Be ready for challenges and strive for the complete satisfaction of your customer (your operational people). Use all your five senses. The best part of being in the mechanical maintenance is that you can see almost everything. Equipments warn you before failing. The worst part is, we usually ignore the warnings and after the failure, the entire effort goes into putting the ball in others court!