Rocky Soil
If you want a home with a basement, you're going to want to avoid building on property with bedrock or overly rocky ground. In those conditions, you can't just dig out your foundation with a backhoe. You will have to find a contractor that can either cut through the layers or blast through them with explosives, the cost of which may not be within your budget limits.
Marshy Soil
If you plan on building your home near a body of water, you should investigate yearly ground saturation. While mechanical dewatering will help during construction, you might have to amend the ground with truckloads of soil and create a drainage system, both of which can be costly. Depending on how marshy the land is, a basement may be out of the picture entirely.
No Contracts
Contact a reputable lawyer to draft up a contract with the businesses involved in building your home, no matter how small they are. This sets in stone not only prices but time frames, and defines contingency plans for setbacks, ensuring that you're living in your new home on the schedule you have set.
Home construction isn't something that you want to do by the seat of your pants. By having everything laid out before you break ground, you can be 100% certain of costs and needs.
No Inspection
While your contractors may be amazing, have someone else double-check their work. A licensed home inspector will be able to guarantee that everything is installed properly and up to code, pointing out if you weren't given the quality service you were promised.
Not only is building your own home cost-effective in some situations, but it is also very satisfying. You are creating a home that is truly yours.