Hmm, lots of answers so far. I'll tell you what has worked for me

Sorry in advance for TMI, lol.
For about two weeks, I was lucky if I went every two days. It was frustrating, I felt bloated and gross, and I just wanted to jumpstart it.
I got some psyllium husk powder from Walmart for about $13 in the laxative aisle. I've been mixing 1 teaspoon in a bottle of water with Crystal Light with breakfast and dinner. It's safe to take daily, unlike OTC laxatives. Basically it's just pure soluble fiber, it'll absorb water and turn into kind of a slimey blob in your stomach (tip: drink it fast before it absorbs too much water) which will add bulk and water to your poo and make it move along faster. This took a few days to work, don't expect immediate results like a regular laxative, but it will work after a few days.
I also noticed that my constipation seemed to start right after I stopped eating a nightly snack of yogurt. So I started taking an acidophilus tablet with breakfast and dinner. That really seemed to be the kicker. I actually went twice today easily (TMI, sorry!). I'll probably keep taking the psyllium and cut back to one acidophilus per day.
Also, I personally find prunes to be delicious, and they do add lots of fiber. Just remember the calories add up...I'll eat 5 prunes for 100 calories.