Modafinil has been one of my favourite drugs since I first used it over 5 years ago. It was during my neuroscience final year and after a lot of research into how to over-ride my need for sleep I found it.
It's a great drug and on the whole, fairly safe for most people. But people who buy it without consulting a doctor first should be careful about any other medication use.
I also highly recommend taking it in very early in the morning. I leave a tablet next to my bed with some water, set an alarm for 4am, wake up and swallow it before falling back to sleep. It takes over 2 hours to reach peak plasma concentration and you will find it wakes you up after about 2-3 hours. This way, the second you start your day you are fully-dosed, and by the time your day is ending and you actually want to sleep, the dose should be wearing off (with a half-life of 10-15 hours).
To learn about how mod works, how to stay safe and check drug interactions and other useful info, please read this article I wrote: http://improveanthony.com/2013/10/29/conqueringsleepwithmodafinil/
Stay safe and good luck achieving! Peter