There are many ways to attract new clients, forget advertising and go out and make and develop relationships with people who will regulary introduce clients to you. The first port of call should be your local banks, speak to the small business managers and create a recipricol arrangement with them. Join a local networking group and play a key part in it to not only attract new clients but to develop your own support network. Try other firms of accountants in your area, see if they want to outsource any VAT, PAYE, bookkeeping as well as an overload of accounts and tax work. Find a niche and aggressively market it, whether it be IT contractors, plumbers, restaurants, whatever. Get a website that is different, is personal to your business, and ranks highly in Google. Offer free consultations and always try and make sure that once in front of a client you close the deal. Be approachable and listen to their needs and that should not be difficult.
Dont advertise to the world at large, too costly, too many price shoppers and too much competiton.
Know when to turn away work, don't say yes to all clients, those that are not suitable to your business say no to even if that is difficult at the start up stage.
Make sure that you ALWAYS define the scope of each engagement within an engagement letter, otherwise you will end up providing more services than originally quoted for.
Tell clients that you do sign up that you are looking for growth and referrals would be welcome. You can offer incentives to clients for this but the best way to get them to do this is by providing an exceptional service that many accountants aren't providing.
Do's: Be proactive, minimise clients taxes, look at more than just compliance work, be flexible, be responsive, treat all clients the same regardless of size
Dont's: Use jargon, keep clients waiting for appointments, miss telephone calls, reply late to emails, surprise bill, file late accounts.
Hope that some of this helps you, but a lot of things you will simply gain from exeperience.