Like I said it's very unseasonal (for us in the UK at least) but it's super cute and looks really cool :). I'll show you the finished look then I'll give the tutorial.
I figured posing with a gingham bow would work ;) my sister made that bow btw....anyway here we go...
All you need is, one white polish, two of the same colour, one lighter and one darker, I used Models Own Lilac Dream and Models Own Purple Poppy. Also you will need one nail art brush either a striper or just a medium length square edged brush and some acetone/remover to keep cleaning the brush with.
Paint all your nails white, two coats should do it, they don't have to be perfect as most will be covered. Then use a fast drying topcoat to ensure a smooth and dry finish.
Once all nails are dry, starting at either edge of your nail with a tiny bit of nail polish on the nail art brush/striper, slowly bring the brush to the tip of your nail, go over it again if it's to thin or wobbly, you need a nice edge. Repeat across the nail, depending on the width of your nail you should be able to fit three thin stripes or two medium sized stripes. Again you'll need two coats on the stripes.
Once the vertical stripes are dry, you can start to do the horizontal lines, try to make them the same width as the vertical lines and space them out so that when the lines cross they make white squares, it doesn't look as good if you have rectangles :P.
Once the horizontal lines are dry, take your darker shade and dap a tiny bit onto the nail art brush/striper and where both lines meet create a square out of the darker colour, this is quite easy as the lines you've already created help keep the darker colour in a sqaure shape. I've shown you here just on the one side to show you what I mean.
Continue making the squares on all cross points on all nails. I only did one coat as I didn't think it needed a further coat as it's a darker colour. As you see my lines and squares are not perfect but it doesn't matter.
Once everything is dry seal with a very glossy topcoat and you're done. The topcoat really helps to disguise any blips and uneven polish.
So I hope you found this tutorial helpful, I'm sure there are other ways to do this but this is the way I did it and it was pretty easy the only difficulty was creating straight lines without a proper striping brush, the only thing is that it is very time consuming and you might get a sore back :P. My right hand turned out pretty good too, the pattern is bigger on my right hand but it still looks good :)