Remember that our species spends 90% of our time indoors. Incorporate healthy and human-friendly elements in the construction and finishing of your new home.
Define what "sustainability" or "green" mean to you and use this understanding to drive your design decisions. Different facets of sustainable construction will pull you in different directions, and it's easy to get lost (efficiency, resilience, emissions, environment, cost, water use, durability, et cetera).
Design your home to suit its climate and location. Homes in the Pacific Northwest need a good hat (roof and overhangs) and good set of boots (below and near-grade waterproofing) to weather winter rainstorms with limited drying potential. Home orientation and location can unlock daylighting, passive heating and solar opportunities, but can also lead to overheating and higher material use and construction costs. Work with nature, rather than against it.
Use natural materials to reduce or negate carbon emissions, improve human health (biophilia) and avoid filling landfills at end of life (composting). If you wouldn't feel comfortable mixing or using toxic building materials, do you really want to live beside them for the next 50+ years in this house?
Avoid foam. The energy savings that foam provides will never offset the negative environmental and health impacts created during foam production and installation.
Think airtight and vapour open. Modern codes rely on air tightness to reduce heat loss (convection). Water will eventually enter your walls and needs a path to dry. Drying ability (vapour open) allows 100yr old farmhouses to remain standing while homes from 1990 and 2000 are tarped and reclad due to moisture issues (leaky condos).
Incorporate rainwater collection and energy production to weather periods of drought and power outages. The climate 100 years from now will be different than today. Plan accordingly.
Minimize concrete to reduce carbon emissions and construction costs. Where concrete is required, reinforce with micro steel fibers to improve durability and reduce foundation leakage.
Live and build simply. Use simple and durable construction approaches and avoid relying on complicated mechanical/building systems to meet your needs.
Push your design/construction team to find creative solutions to meet your green building goals. Do your research. Shoot for the stars (Living Building Challenge construction criteria). And when budgets tighten, allocate funds to the primary building systems and elements that can't be easily changed or updated in future.