You can make less extensive alterations that will still make a real difference in the appearance of your home. Properly scaled and styled, dormer additions are a major but manageable cosmetic improvement. They not only change the look of the roofline, but they also provide better lighting and increased floor area inside. Look to the edges of the roof for other opportunities. Changing the depth of the eaves, widening or applying trim to the overhang and boxing in the underside of the eaves to create a soffit are some ideas that will bring a new look to the house.
Simplicity is the key to using building materials effectively.
While in many cases new siding can be installed over the existing material without much trouble, don't overindulge. In fact, using just one material is perfectly fine, and will allow you more freedom to work with trim and color. Avoid butting different siding materials together. Designers do it only if a wall jogs and the offset is at least 12 in., such as where an addition meets the original part of the house. Consider the role the roof plays in the picture, too, especially if you're thinking about having it replaced.