My best advice is to take it slow. Don't start out full speed or your calves and achilles will make you pay. Start out walking around a bit and work up from there. From what I understand you can do pretty serious damage to your achilles tendons if they don't have time to adapt to the new load your putting on them.

I'd suggest regular walking several times a week for a month or so before you start running in them. I did this (I was recovering from a back injury at the time, so I had to take it slow), and had zero issues. Most of the Vibram injury stories I've heard have been from people who didn't listen to the take it slow advice and over-did it at the outset.

The answers to this question might be helpful, there's a link to an article on getting started as well: http://paleohacks.com/questions/22892/vibram-toe-pain

Whatever you do... DO NOT do 800M sprint time trials in the first week haha. I bought mine last year and have never looked back but when i got them, i wore them around the house for a couple of days, then walked my dog in them for a couple days. This did not prepare me for my first workout. I do Crossfit, but the workout that day was 4x 800M sprints at max effort. I felt awesome running and did quite well compared to old times, considering how much you change your stride from traditional running shoes, but my legs were crushed for DAYS. Looking back, i wish i had either skipped that workout all together, or gone for very light jogs instead of max efforts. My advice is to build up from very short, light jogs, to longer runs, then eventually sprints over time. Go by how your feet and legs feel.

I love my trek sports and wear them as much as possible. My suggestion is to wear them for at least a couple of casual 2-3 mile walks before going full bore run in them. You need to learn how to "midfoot strike" instead of heel striking (common for shoe runners). Fortunately (at least in my case) it doesn't seem to take that long.

It is important to get the right fit, if they are too big they will rub and be uncomfortable, the toes must not (or barely) touch the ends of the toe pockets. It is easier to stretch them if one foot is slightly bigger than the other - push a pencil and tissue tight inside the toe you need to stretch, or clamp them to a DIY table and steam with a kettle or leave for a couple of days. It really works.

I agree with everyone else, go easy! walk around the house for the first few days and then try rougher terrain, do not run too far to start with, build up slowly. Running on concrete is the hardest on the feet, but after a few months, this will be no problem.

I was very stiff in the ankle area every morning for months, but that passes. The only time I do not wear them now are if it is very cold with snow on the ground, but I have just ordered a pair of vivo barefoot hiking boots for the colder months, they have lovely boots too. The VFFs are very uncomfortable if they get wet and cold, even the FLOWs which are supposedly warmer with 5mm soles instead of 3mm, so I always take a spare pair with me when I hike and change them half way through, just so I can get a little more comfortable and dont start to get blisters.

In summer I wear sprints (and classics for dressier occasions), and love them, though be prepared for the comments. They never fail to start a conversation with people on the street.

To start with I had cramps all along my foot arches, sometimes really bad, but this passed after about 3 weeks and I guess it was because I was starting to use muscles I hadn't used since I was a child. I also got my little toe caught in a pram wheel which was really sore, so you have to be aware of your toes getting caught in things like branches etc.

The overall feeling of freedom I have now is amazing, I love walking and hiking up in the mountains with them on feeling every stone underneath my soles, gripping every root and bolder....it is wonderful.

I do not plan to buy any regular shoes ever again.

There is loads more info on the Birthday Shoes site, about purchasing and fitting VFFs and other barefoot shoes, people's experience with them (with loads of photos) and news on new products - they are planning on bringing out VFF boots this year, but I think they look hideous ;)

there is even a forum where you can ask questions and swap one shoe with someone else if you have feet that are two different sizes.

Great shoes. My first pair were the kso treks with the kangaroo leather.. Nice but terrible if they get even a little wet.

My second pair is the kso's. Love them. Great in any environment. I've been here in south America with them. Love peoples reactions to them

I have been wearin them for about 8 months. I have lost a shoe size due to my feet stregthening and arch increasing

My little toes were really sore at first, but that went away after I wore them a few times. Also, don't overdo wearing them too much at first or working out too stenuously with them on. Give it time.

There is a huge difference between walking and running in Five Fingers. That is to say, when it comes to running, take it slow at first, and build up your distance. Your calves will thank you for it. You'll slowly adjust to not landing on your heel in these shoes, and landing fore or mid-foot instead. Consciously thinking about it, while jogging, will help, or if you have access to a treadmill and mirror, you can watch yourself and adjust accordingly. After a few runs, when your pace picks up, you'll naturally fall into the proper landing because heel-stomping will hurt.

Walking is a different matter entirely, because when moving slowly, you still tend to land heel-first , so there's not as large of an adjustment. Most people won't experience soreness from walking around in Five Fingers like they will with running in them, so there's no reason you can't start wearing your new Five Fingers around for casual use immediately.

FWIW, our initial experience is noted here: http://mendax.org/2010/03/19/a-five-fingers-journal/

Since that post, we purchased three more pairs (different styles) and swear by the shoes. Wish we could wear them at work.