I think the most important thing when it comes to constipation is hydration. I was feeling constipated for a long time. I started recording my water intake to make SURE I had at least 8x8oz glasses of plain water a day, and about a week later, was back to a healthy restroom usage!

Also, be careful of laxatives. Even more natural ones like senna, you need to make sure you don't use them too often or too long, or you could become dependant on them. Just don't overdo them.