
1) Identify your objective
What do you seek from a marketing consultancy? What are your goals? Do you want a campaign strategy or PR development? An ongoing relationship with the agency or a one-time affair with the development of image materials such as logo, letterhead, web site, newsletter templates or any other client service. A good habit and insight to offer your agency is a sales target document or company vision. 

2) Budget and Cost
Establish what you can spend. Unfortunately many businesses, especially startups do not and end up in bankruptcy. Avoid that grim fate by wisely allocating your advertising budget. You may get a less attractive promotional package but think long-term. Whether it is acquiring email campaign services, social media promotion or creating TVC’s, all can mean nothing if you are left broke in the end. You can increase your marketing budget overtime with each successful campaign and profits. A smart strategy would be to divide your budget based on the percentage of the anticipated sales volume you expect annually, quarterly or from one campaign, as per your requirement. Patience is key! The choice of agency is also essential. A respected market giant will obviously charge as per their reputation. On the other hands those prices are also associated with elite services. 

3) An insightful look
Inquire about what you are getting yourself into. Question experts, coworkers and on online forums. There are several ways you can get information about advertising agencies from experienced clients. From competitors and trade publications to Yellow Pages and Companies themselves. Question potential agencies with a list of current and former clients. Contact these clients for their experience and learn whether the agency was of value and helped create brand awareness and eventual sales for them.