The main element of any structure is the foundation. It must be strong and durable. You can build a foundation with your own hands if you have some building craft skills.
Before proceeding with the construction work itself, study special articles and recommendations that relate to such a topic as building a foundation. The strength and service life of the entire structure depends on how correctly the foundation is made. A poor-quality foundation cannot be corrected at subsequent stages of construction, so a negligent attitude to its construction in the future will lead to incalculable financial losses.
After you decide on the type of foundation (columnar, tape, slab, pile) and learn as much as possible about the theoretical side of the issue. You can start building.
Mark the future construction site. Fence off the area where the house will be located. Dig a trench 30 to 50 cm deep along the perimeter of the outline of the future building. Make a sand cushion.
Next, install the formwork from sheet plywood or durable boards. The formwork must be strong and reliable. The resulting recess is filled with concrete and the surface is leveled. Foundation ready. You can start building your own house.