I am actually not so sure about the cages advice. Of course foot retention is an absolute must if you ride brakeless. But it might be a bit much at a time to get used to the fixed gear and cages at the same time. If fixed gear gives you a hard time at the beginning, I would ride with two brakes (and use them!) and no foot retention until you feel perfectly comfortable with the fixed gear. Then put on cages or straps and try braking with your feet. Once you're good at that, you can take of your rear brake if you want. Just a suggestion of course, all roads lead to Rome I guess.
I am actually not so sure about the cages advice. Of course foot retention is an absolute must if you ride brakeless. But it might be a bit much at a time to get used to the fixed gear and cages at the same time. If fixed gear gives you a hard time at the beginning, I would ride with two brakes (and use them!) and no foot retention until you feel perfectly comfortable with the fixed gear. Then put on cages or straps and try braking with your feet. Once you're good at that, you can take of your rear brake if you want. Just a suggestion of course, all roads lead to Rome I guess.