A house construction consists of trades. Civil engineering. So foundations, slabs, basements, piping, connections. Own contribution? Structural work. So masonry, plaster, screed. Own contribution? Carpentry, so roof truss, doors, window frames, drywall ceilings. Own contribution? Roof. So roofing. Own contribution? Electrical. So sockets, cables, solar, if photovoltaic, light outlets, switches, telecommunications, satellite systems. Own contribution? Plumbing and heating. So gutters, drainpipes, solar thermal, building technology, heating systems... Own contribution? Bathroom and sanitary, so ceramics, showers, tiles and tiles. Own contribution? Painting, wallpapering, floor coverings, filling. Own contribution? Built-in furniture, especially kitchens. Own contribution? Self-assembly? Garden and landscaping, so paths, terraces, embankments, paving, lawn, fence etc. Own contribution? Systematized like this, it may be easier for you to enter what you want or can do yourself and what not. There are certainly a number of DIYers who can manage bathroom, sanitary and tiles themselves, but few who can handle civil engineering or roof themselves.