You could have the best skills and the lowest costs in the industry but if you do not know how to treat clients and contacts correctly you could very quickly find that your client base drops and you will constantly have to find new sales to keep yourself afloat. It is far better to leverage your current clients as a source of new work and referrals.
Firstly remember that the people you deal with are just that - people. No one likes to be taken for a fool or treated badly so show respect for your clients! Observe deadlines, make calls or emails when you promise too and never try and take the customer for a ride, quite often a customer will have more than one potential supplier for any job and your competitors will happily tell your client if you have told untruths or are over costing jobs.
Telephone manner is always extremely important, especially when making initial contact with a new potential client. Politely introduce yourself and explain why you have called and then ask if it is a convenient time to talk, this immediately places you as a person who thinks about their clients and does not push their sale too heavily. If the potential would prefer that you called back at a more convenient time then make sure you diary the call and make sure that the call is made as promised, this time demonstrating your ability to keep your word and your strong organisational skills. As previously mentioned it is a great idea to mix business with pleasure, a straight business call is never fun; try to find out some personal information about your contact - the kind of hook you can use when you call back again such as their family and interests. This will place you as a human, making it much easier for the client to treat you as a person and not just another salesman.
Word of mouth and personal recommendation will be one of your most effective ways of generating business so always bear this in mind. New business from existing clients is well known to be so much easier (and cheaper) than sourcing new clients so make sure that your clients know that you would be more than happy for them to refer you on to their clients and customers if they are happy with your service. Some freelancers even offer referral fees or gifts, if a client of yours introduces a new potential to you that leads to paid for work why not reward them with a bottle of bubbly or an hour or two off their next assignment as a way of thanks? It will please the client no-end and will also make sure that you are fondly remembered if another chance to refer work comes your client's way.
If you have your own Limited company have you ever considered taking clients and potentials out for lunch or to other areas of interest to the client e.g. to watch their favourite team play or to play a round of golf? This is an excellent time to really get under the skin of the client and to get a good few credits in the "emotional bank account" (see below). Just as importantly make sure that you retain receipts for these activities and claim back the VAT as entertaining clients.
This is a great formula that really works! Every time you do something to delight a client it is like a positive transaction into your bank account, they will grow to like you not just as a service provider and will treat you more favourably. Having credit in this account is also very useful if you need to draw upon it, imagine that business has really taken off and you will not be able to produce one of your regular tasks on time, calling your client to ask if the work could be provided at a slightly later time (agreed deadline with the client of course) will almost always result in "Of course that will not be a problem." This account should not be abused though, life becomes more difficult the more you have to postpone work and call on your client's good nature, this will often result in a negative balance and a client that begins to ask themselves "Where can I find a reliable supplier." Just like real life a positive balance can quickly drop into the red if not used wisely and grown at every opportunity.