My parents built a house. They got help digging the foundations (which required heavy machinery given it was built on rock) but did everything else themselves. A couple of tips:

- They bought a pretty run down shell as their first project to learn about bricklaying, roofing, electrics, plumbing etc. before buying the land for the new build.

- For the new build, they got an architect to review their designs pretty thoroughly, given the country's strict building regulations.

Also, don't underestimate the enormity of the undertaking. It took them 9 years to complete the build, working most evenings and weekends after work.