I just built my house (did the contracting myself). Good points already have been made, but I'll add a few.
1. It is easy to get bogged down on interior decor choices - so many choices, colors, materials. Try to get these settled early in the game. It is not an issue if the builder gives you packages. I used Floor & Decor designers (free) and Sherwin & Williams paint consultant ($100) to get me off of high center and made sure everything flowed.
2. When setting driveway and sidewalk forms, have them lay a 1.5" pvc pipe crosswise in case you want to run wiring underneath later. Mark location with a bit of porch paint on the sides of the concrete.
3. Take photos of locations of water and waste lines, cable lines, underground power lines etc. Don't rely on memory.
4. Windows - consider High-Performance (HP) Low-E vs regular Low-E. HP Low-E will cut down on heat transfer but are darker (look at VT spec to see how much light they let in) and they cast a bit of a tint indoors which affect paint colors. See photos at
https://www.houzz.com/discussions/2637495/does-low-e-have-to-tinted-glass. 5. Run at least 1 cat-6 and coax to each room. Cat-6 can power low voltage devices. Have all cables (ones leading outside and inside) terminate in a designated cabinet or cubbyhole indoors, for easy access and to prevent cooking your router in the attic. Use conduit to run the cables outside and to the cabinet in case you want to add to them later.
6. Consider doing the landscaping yourself. Locate a wholesaler - I bought most of my foundation plants for $10 each. This is something you can take your time with unless an HOA is on your case. Make your planting beds deep enough so they are scaled to the size of your house and yard.
7. Get fiberglass exterior doors; metal doors will get scratched and expand\contract with heat and wood doors may warp and degrade. My wood pattern fiberglass doors look like the real thing.
8. Consider ridge vents for attic ventilation. They move more air than whirlybirds. Don't use powered attic exhaust fans (fire hazard).
Finally, once you start don't second guess your choices. It will be costly with change requests and drive you crazy.