1) Never install hardwood flooring over under floor heating systems.  This can cause wood to bend, twist, split, shrink or even warp. 2) If installing hardwood over subfloor that is concrete make sure you wait until concrete is fully dried out.   If installed to quickly moisture from the concrete can be absorbed by the wood causing warping, expansion and bending.  Humidity levels should be at least less than 6% to ensure proper installment conditions. 3) It is not advised installing hardwood flooring in areas that are consistently high in humidity; such as basements and showers, because these are high humidity areas wood is more likely to expand and warp and may even reduce the lifespan of the flooring. 4) Make sure you have sufficient expansion space between plank edges and walls.  Wood is sensitive to temperatures and humidity depending on different factors.  Wood expands and contracts so you will need to leave enough space to allow for that, I generally recommend leaving 1-2cm for expansion gaps, this will allow the wood to expand and contract without any bulging, bending or cracks. The edges are normally covered by kick-board so you don’t have to worry about it looking “ugly” per-say!