This is not a short subject, but I will give it a shot, trying to stay at the 50,000 foot level.
1. Define your equipment - What level of detail do you want to view equipment maintenance and failure history? This is critical. Maintenance personnel will need a lot more detail than fixed asset accounting. They will share the same table, but there needs can be very different and often conflicting. Make sure you are working with an implementation consultant that understands this.
2. Define your current work processes - preventive, corrective maintenance practices. What are the critical features of your maintenance work process? How are you using work orders today, what information are you collecting from them, and what are you not getting that you want? Here again, maintenance shares functionality with manufacturing and accounting in the work order system. Close coordination is required to make sure requirements are met and conflicts are avoided. Make sure you are working with an implementation consultant that understand the differences and competing interests between simple, manufacturing, and maintenance/service work orders.
4. Make sure that your inventory analysts understand the differences between MRO and production inventory. The way you set up your MRO inventory will be similar to, but may have significant exceptions from, the way that you manage production procurement and inventory. The maintenance implementation must work closely with your distribution team so that both teams understand impacts.
5. The ease with which JDE maintenance is implemented is directly related to the maturity level of the maintenance program to be run on it. If your current maintenance management system already has detailed equipment records, a work order management system, and a preventive maintenance program, there will be a lot less work involved than if you are trying to develop these business processes at the same time you are implementing the software.
Let me know if this helps.