I do hair and beauty but not nail enhancements or threading. Any calls I get re: threading or enhancements I pass on to friends. I also do this for hair extensions which I also don't offer.
Might be an idea to co-operate with other professionals offering things you don't, that way you all get to recommend each other.
Another route I have found very successful is to advertise on local gumtree, I'm averaging one new client a week and usually getting recommendations from them too. You can post pics of your work which I think definitely helps.
Its also an idea to drop leaflets in student halls of residence, especially after xmas as they're all back with their bit of christmas cash. I prefer to offer party booking prices rather than student discount that way you can make one trip, do numerous people and make a fair whack even with a discounted rate. (also saves you dragging your stuff back and forth for seperate bookings)
I also do alot of muslim ladies (good market for hairdressers as they can't show hair and not alot of 'closed' salons about) Many (especially if their english isn't good) prefer to have treatment at home, its more convenient and they often have children so salon trips are hard work. It can take a bit more time due to communication issues, but lots of books with pics, colour charts etc. overcome the problem. Once you impress one lady your name will soon get around.
Hope it picks up for you soon X