Experience is the key
If you’re a business, that’s attempting to roll out a SharePoint project solely in-house or migrate to a new platform, then you’re going to need the whole business behind you, a lot of technical expertise, your best planners, and everybody pulling their weight.
The architecture of the infrastructure that will host your environment is crucial to delivering speed. Setup and configuration covers a multitude of sins from the central administration, security and accessibility, backups and testing backups, and knowing what to use out-of-the-box and what to customise instead.
If you’re migrating to a new platform, make sure you are aware of the fundamental differences between versions.
Then there’s thinking about how the system will be managed, who governs what area, what will the logical architecture look like, how will data be populated, how will the business gather the metadata to drive the search.
Once you’ve worked all that out, you can then think about building the structure of the site and set up of farms, site collections, site columns etc, and finally the visual interface, branding and training.
This represents an overview of the process and by no means lists every step.