I maintained a home-grown corporate ERP for ten years. The most important takeaway from that job applies universally. Business software must reflect business

I maintained a home-grown corporate ERP for ten years. The most important takeaway from that job applies universally. Business software must reflect business processes. If there are no processes, how do you know that your software is going to enable people to do their jobs? Every business unit, every department, everything everywhere needs business processes that are documented. Those documents need to be maintained as the processes naturally change to reflect changing business needs. Those process changes need to be reflected in the software you're going to be working with. If your company does not have the corporate will to establish and maintain processes and back the steps needed to keep those processes in step with reality, then any attempt to establish an ERP - whether homegrown or adopted from a vendor - will fail. Likewise, trying to maintain an existing ERP without corporate backing for process management can be incredibly painful. Directly related, go with a vendor if you possibly can. As others have said, your business processes are usually not unique. There are adequate SaaS and FLOSS-with-support/FLOSS-with-premium-bits options available, and you as the implementer should give them a huge amount of weight compared to huge monolithic scary things like SAP.