I would recommand to build one with help from someone more experienced. Just don't ask him to build it for you, assist him in doing so. You will learn a lot and you will be able to fix it yourself in the future.
The only tricky parts in a fixed gear bicycle is the headset, everything else is straightforward. Well it's not that tricky but your life depends on it so I wouldn't tell a newcommer to install his first headset without assistance.
I would recommand to build one with help from someone more experienced. Just don't ask him to build it for you, assist him in doing so. You will learn a lot and you will be able to fix it yourself in the future.
The only tricky parts in a fixed gear bicycle is the headset, everything else is straightforward. Well it's not that tricky but your life depends on it so I wouldn't tell a newcommer to install his first headset without assistance.