I've actually experimented with no-poo. The first time was actually over many months where all I would use to wash my hair was water. The second time was a brief experience with Hair One (supposedly similar to Wen, another no-poo product. I can give you some advice to make it work.
First, if the water you use is hard, has lots of minerals, chlorine, etc., you are less likely to see good results from no-poo. I specifically had to stop my water only wash regimen after moving to an apartment with very hard water. It would cause a lot of mineral buildup in my hair. If you have soft water, that's good. If you have soft water WITH a filtered shower head, that's even better.
Second, the more hair you have, the harder it is to go no-poo. No-poo requires a lot more effort than regular shampoo/conditioner.
Now, here is how you go about doing a water only wash, which I actually highly recommend if you have good water and the time to do it:
1. Before you shower, run your hands through your hair as much as you can. Shake your head. Scratch your scalp. The idea is that you want to try to knock out as much dirt, dead skin, and loose hair as you possibly can.
2. Use a boar bristle brush and brush out your hair a lot. You might have to be pretty rough, especially on the scalp. Just don't hurt yourself! Haha. Again, the idea is to get out as much dirt, dead skin, and loose hair as you possibly can.
3. Once you are in the shower, you will go through 3 "stages" of using water to wash your hair. First, wash cold, then hot, then cold again. Each time will use the same process. Each "stage" should take at least a minute, if not two. What you want to do is use your fingertips (not your nails) to really dig in/massage your entire scalp to clean it. Also, run your fingers through your hair to use the water to clean the hair strands as well. Since you aren't using shampoo, you really need to spend a lot of time working your scalp and hair to clean it. Again, same process, just done 3 times (cold, hot, then cold again).
4. Once you are done showering, thoroughly dry your hair with a towel.
5. Use the boar bristle brush on your hair again like before you showered.
Note: Clean your boar bristle brush every time after you use it (yes, even before and after showering) to remove the junk it collects. You don't want that going right back into your hair.
It can take anywhere from two to six weeks before your scalp and hair normalize to your new washing conditions, but following these steps should make the transition as easy as it can be. Personally, my hair adjusted in less than two weeks and only felt a bit greasy and grimy (it actually wasn't) for a few days. For the few months I did the water only hair washing regime, my hair had never looked and felt better. It was always very soft, smooth, and shiny without ever being greasy. My hair was noticeably less greasy over time even without showering. Anyone that smelled it said it had a very natural, pleasant smell to it, though I'm not a particularly active or sweaty person.
Like I said, if you have the right water, time, and motivation to follow this, it's probably the best thing you can do for your hair. I wish I still could. It was worth the effort.
Now, I also tried Hair One. The directions are pretty straightforward. It takes a LOT of product, and it's not cheap (Wen is even more expensive). It also takes time and effort, though arguably less than the water only washing. There are several types of Hair One cleaners/conditioners. I only tried the argan oil one, and it was OK. For me, it made decently shiny looking, but it wasn't as smooth as some shampoos I've used (certainly not as smooth as water only washing). It made my hair feel light and clean, but also drier and more brittle than the shampoo and conditioner I was using previously. It felt like it was getting progressively worse the more I used it, so I stopped. That, and it wasn't worth the time and money for how my hair turned out.
Anyway, those are my experiences with no-poo. I'm sure I'll try other products and techniques down the road.