A simple way to get fit for HIIT is to start on a treadmill.
My routine is 1 min of 12 kmph followed by 30 seconds at 6 kmph, I repeat this over around 8 times and it takes about 12 mins total. Nothing like this at the end of a gym workout to really get a good burn.
I do the HIIT only once in a while. What I do is that I start from 5 mins (using the 500m average time program on Concept 2), then decrease 1 minute everytime but try to increase the same level of intensity in each stroke. I get 10 seconds rest between each interval
Sometimes variations would be used and it would start from 10 mins with 30s rest between each interval, which is a pretty long time to rest actually.
I like using HIIT training on the rowing machine. The high intensity helps build my fitness and raises my metabolism for days after. I do high intensity interval training for 10-12 minutes. Any longer and the intensity isn't high enough!
I don't do HIIT a lot but it is a great way of burning fat. The beauty of HIIT is that it can be done anywhere and it takes very less time. I used to do it when I had an incredibly busy schedule but now I have moved to more intense workouts. Still there's nothing like HIIT to burn some fat quickly.
I do HIIT once or twice a week. I have tried HIIT on the rowing machine, but usually I run for HIIT. I complete the HIIT workout in 12 minutes, sometimes 10 minutes. I jog for 1 minute and sprint for 30 seconds. It is very intense and demanding, I sleep like a baby afterwards.