Lots of great tips on here, but for those of us with problem nails, thin and weak, ridges etc or that want their nails to look great without nail varnish on, then can I recommend these
www.boots.com/webapp/wcs/stores/servlet/ProductDisplay?storeId=10052&productId=12364&callingViewName =&langId=-1&catalogId=10551
Many other places do them, Asda do a smart price one for about 80p, some may be normal nail file shape, but have 3-4 different surfaces on them.
These are great, they smooth and condition your nails and add a great shine, and encourage growth too.
I have them everywhere, bathroom, bedroom, handbag, so if I get a spare minute I give them a buff.
But the best thing is the price- it's alot cheaper than a manicure!
use it with a orange stick to neaten your cuticles and handcream and voila a manicure without the hassle and expense.