I have a portion of my room I need to make a shelf for. Because of how the area's laid out I can't just buy a desk with shelving built in, it needs to be a shelf without much depth. I don't have tools, an area I could use them if I scored some secondhand, or friends who do woodworking so I'm wondering what common points of failure I would run into if I were to make 2-3 trips to Lowe's or Home Depot and bought my boards pre-cut, then assembled at home. I have the basic knowledge to assemble this (drill guide holes with a bit smaller then screws, then apply wood glue to the area two boards attach before screwing them together completely) and can follow a sketched blueprint and cut list. So far I've only come up with needing to factor in the bit of board the saw blade eats, and can just measure the next cut's length one at a time instead of laying a board out, walking down it with a measuring tape and pencil. What other common points of failure should I be aware of, anything?