Remember the basics: You want your marketing to help you attract (and retain) profitable clients who fulfill your business objectives.
Therefore, your most successful marketing starts with your best current clients: Knowing what they like and value, and delivering it to them in a manner that at bare minimum is exceptional and ideally is over-the-wall “wow”.
You can’t ignore developing new clients, of course, and never want to be so tied with one or only a few clients that their departure can destroy your business. However, all the energies you spend reaching out cold for new business will produce a fraction of the results of a bit of effort to cultivate and encourage repeat and referral business.
And if you are looking for the highest and most effective way to reach beyond your current clients, consider client-focused community and association participation and support before you spend money on more expensive and less effective strategies.