The standard position for blocks is to leave three empty rows between the blocks and the ground, or another set of blocks, beneath. There are times when blocks may be placed higher or lower, but these are the exception to the rule.
The most natural way to place a semi-solid platform may be to set it directly on the ground. In some cases (especially when working in the Super Mario Bros. 3 style), this works well. For the dirt hill platforms in Super Mario World style, this results in awkward-looking hills.
When creating a sub area, be aware of the length of the level. This is especially important when a level has only one entrance/exit for the sub area.
Floating pipes first appeared in Super Mario Bros., in World 5-1 and World 6-2. These appearances set the initial foundation for a floating pipe. The Lost Levels further defined their use. Following the rules set by these games will improve the appearance of floating (and hanging) pipes in levels designed using Super Mario Bros. mode.