You can increase your sales by using advertising and promotion as part of your marketing strategy. An advertising agency can help you, but they will charge a fee. Given the broad range of advertising options available, it pays to get good advice from a reputable agency if you want to ensure your campaigns are effective. Before you choose an advertising agency, you should:

find out the size of the agency
check if they are members of any professional associations
ask what media they specialise in and if they have any particular creative strategies they prefer to use
examine their past campaigns and find out how successful they were
look at their types of clients, past and present
ask about the main people who will be working on your account and their track record
see if they have any experience of working for your type of business and if they understand the competition in your field
check how they assess a campaign’s effectiveness
get an estimate of their fees and what’s included – eg whether they would accept a payment-by-results agreement
take up references from their clients if possible