Hello
In the first 6 months of being self employed (especially in the beauty industry) you will break even with the initial outlay of products and equipment, some people it will be longer than that depending on what has been purchased. Ensure that you are registered for self-assessment (if you haven't done this already as you must do it within three months of starting) for tax and keep your receipts and records in good order.
Firstly look at every treatment on your menu, work out what it costs you to carry it out, include products, consumables, electric, also don't forget to cost in things like your insurance, and any costs if you work mobile (fuel, car tax etc) put this information in a spreadsheet with the time it takes you to carry the treatment out. This will give you a good insight into how much things cost and what you should be charging.
Do some analysis on every single person who has come through your door, look at your appointment and client records and look at your treatments through from the most popular to the least popular, put them in a spreadsheet with a number of visits beside it. Look at what has worked and why, and what hasn't worked. Never do offers on what has worked and try to boost interest on what hasn't worked. This could be some free nail art or glitter on a certain gel polish colour (if it hasn't been that popular) or a free cleanse, tone and moisturise (this will introduce a person who doesn't usually have facials to your skincare brand, you can also do a quick skin analysis at the same time) do a proper consultation and give recommendations.
Take email addresses and Birthdays from everyone who walks in your door, email them with some well thought out marketing emails, e marketing is free and very effective. Send them a 10% voucher (or something similar) a week before their birthday.
There is also a thread on here
http://www.salongeek.com/biz-geek/83160-more-ways-promote-your-business.html that will be useful to you.
Michelle x