This is something I've been meaning to do as an accent nail for a while with loose glitter I bought on Ebay (from here) but I'm a bit of a football widow at the minute so I decided to go the whole hog. It's ridiculously easy to do.
All I did was paint my nails with two coats of a metallic polish that dries fairly quickly (from Topshop's first ever make up collection, back when I'd just started blogging, aaaw!) and then while they were still quite wet I dipped my nail in the bag, onecatca time obviously. I then pressed down the glitter, left them to dry and then brushed off as much excess as I could. Don't worry a lot of the remaining excess just kind of falls by the wayside as you go about your business.
WARNING: you WILL make a mess and you'll be finding glitter everywhere for days so try and contain your working area. I did it on a magazine to try and reduce overspill, it didn't really.
I think these are probably the glitteriest nails I've ever had. They may be a bit OTT but I love them!
This actually feels a lot less gritty than I would have expected, still a bit rough though. If you like wearing woolly jumpers or playing with your hair a lot, this probably isn't for you, the glitter gets caught on stuff. It's kind of a high maintenance mani and would probably be better sealed with gel (as long as it didn't reduce the bling!).
In terms of longevity, I had this on for a few days and it got less blingy the more I wore it. All in all a simple, cheap and high impact nail look that I'd say is good for a night out...I wore mine to work and got a few comments!