One of the things we introduced some time ago is that whenever a project is proposed (large or small) a quite detailed project assessment is required before a final decision is taken. The assessment looks at what would be required to deliver the project (costs, permissions, staff time, etc.) as well as identifying benefits, risks etc. Not exactly rocket science but something that our parish hadn't done formally before. It concentrates the mind about what steps are necessary to deliver the project and what the risks are (e.g. difficulty in getting contractors or need to obtain County Council approvals for example) so that expectations are realistic and necessary resources are appropriately allocated; staff and councillor time in particular. Once agreed, at every meeting there is a report on progress (can be a simple "nothing much achieve this month") which is made by the clerk usually but we also allocate a lead councillor to oversee any larger project who may deliver that report.