Try raising the stem. Lower or raise the seat. 3. Consider your saddle. Consider your grips or your handlebar tape if you have hand pain or numbness. There are many options - foam grips, cork tape and so on.
Gloves can also help.
Consider your tires. Wider tires will give you a smoother ride. 6. Consider your fork. On a mountain bike, a suspension fork will help ease the bumpy ride. On a road bike, a carbon fiber fork will help smooth out road vibrations.