The majority of North American roofs have historically been constructed with a slope between about 4:12 and 9:12. Roofs at the lower end of the range (about 4:12 to 6:12) are relatively easy to walk and work on. (As always proper safety equipment and precautions must be followed when working on any roof).
International building code guidelines recommend a minimum roof pitch of 1/4:12. This means that for every 12 inches of the roof's run—which is the horizontal distance it travels as it covers a home—the elevation of the roof should change by at least 1/4 of an inch.
For hurricane prone areas, the best roof pitch for high winds is 30 degrees, as this pitch can help the roof resist wind uplift. Reducing the overhang of the roof can also help reduce the damage from wind uplift
Over time, the seals and flashing can deteriorate, providing an opportunity for water to penetrate your roof. Things like rain, snow, and debris can accelerate the process. Modern skylights are less prone to leaks than older versions, but even the best skylight can leak if it isn't installed properly.