Here's some random feedback from building my own computer:
-Investigate thoroughly what you're buying from different vendors. Often what looks like a good deal is due to the product not coming with standard things (driver disks, manual, cables, etc.)
-Have a technologically gifted friend. This is a must.
-Good google skills will get you far. Know how to search for exactly what you need to fix problems.
-Be fragile, but firm. A lot of parts of the computer require quite a bit of force to install them inside.
-Don't build your own computer if you need a new one fast. This is a process that can be very time consuming over a long period.
-Do research on tech stores in your area. You usually can get a better deal on parts online, but if you only need one last thing you don't want to wait an extra week.