Several things to consider. First, are you going to go to a neighborhood owned by a builder and have that builder construct a home from their plans for you. If so, that is pretty much routine and you just choose from various options (type of carpeting, color of paint, wallpaper, appliances, etc.).
Second, if you are going to purchase your own lot and then find a builder, you should interview several builders. My ex-husband (we are friends) is a custom builder and he builds for people on their own lots. He helps you secure financing, but you are the one who obtains the loan, receives the draws and pays the subcontractors. This way, you control what is paid and there is no additional surcharge added to the builder. He charges a flat fee for his services of scheduling and supervising the subcontractors...plus, he has some very good subs who do work for him. His customers have been very happy, because they are involved in the entire process, but they don't have to worry about scheduling or about getting good subcontractors.
One comment about being your own contractor. Unless you know something about homebuilding, you may not be familiar with the order and scheduling of what comes next. It's not that you couldn't do it; however, it may not be something that you want to learn the hard way on your own home. Also, you may not be familiar with various subcontractors (concrete man for slab, plumbing work, electrical work, carpentry, bricklayer, etc.). Those contacts are something that an established builder will already have.
Finally, I have been a real estate/mortgage banking/title attorney for 20+ years. One thing that people don't realize is that under the Texas Constitution, there are very specific and limited ways in which you can create a lien on your homestead. This is important if you want to borrow money to build the home (does not matter if you have the cash to pay for it all yourself without a loan). In order to borrow, the bank will want a valid lien. Under Texas Constitution and statutes, you cannot act as your own contractor and create a valid lien. I have seen instances where people started to build their own house and then decided it was too difficult. Then they hired a builder to "complete" it. Unfortunately, the bank would not loan money, because they cannot get a valid lien (mortgage) on the property, because the homeowner started the construction. It is somewhat more complicated, but you should speak with an attorney before you decide to build your own home. This is especially important with regard to other things involved in construction and construction liens.
If you ever want to talk more about it (or if you would like to speak with my ex about building), feel free to email me at ____@____.com or call me ###-###-####). Good luck in whatever you decide.