Define the job first
Document the process, the people using it and the result it should deliver. Separate essential requirements from preferences before comparing products or development options.
Consider fit and flexibility
Existing tools can be appropriate for common needs. Custom development may make sense when a distinctive process or integration requirement cannot be supported well by available options.
Compare the full cost of ownership
Include setup, migration, integration, staff training, maintenance, security and future changes. Consider who will support the system and how easily the organisation could change direction.