It is easy to see other businesses purely as competition, but many of the businesses around you are not competitors at all - they serve the same kind of customer as you do, without offering the same thing. A plumber and an electrician, a wedding photographer and a florist, a cafe and a nearby bookshop, an accountant and a solicitor: each has customers who quite naturally need the other, and neither is trying to win the same sale. That overlap of customers without overlap of offering is the basis of one of the oldest and most effective forms of low-cost marketing there is, and it is sitting unused all around most small businesses.
The idea is simply a referral relationship: an arrangement, formal or informal, where complementary businesses recommend each other to their customers. When your customer needs something you do not provide, you point them toward a trusted partner; when that partner's customer needs what you offer, they send them your way. The referrals that come from this are unusually valuable, because they arrive with trust already attached - a recommendation from a business the customer already deals with and believes in carries far more weight than an advertisement, and the customers who come this way tend to be better matched and readier to buy. For the cost of a conversation, each business effectively gains a stream of warm introductions.
Setting one up is refreshingly unglamorous: it is mostly about identifying the right partners and building a genuine relationship. Think about what your customers need before, after or alongside what you sell, and which nearby businesses provide exactly that without competing with you. Then actually talk to them - introduce yourself, be clear that you would happily send suitable customers their way and would value the same in return, and make it easy for them to refer you by ensuring they understand what you do and who you are a good fit for. The strongest of these partnerships rest on real trust: you only refer people to businesses you would genuinely stake your own reputation on, because a referral is a small loan of that reputation.
Kept up, these relationships compound in a way advertising rarely does. It helps to reciprocate generously - to be the partner who actively sends good work rather than only receiving it - to occasionally remind each other you are there, and to close the loop by thanking a partner when a referral turns into a customer, which keeps the goodwill flowing. A handful of solid referral partnerships with the right complementary local businesses can, over time, become one of the most reliable and lowest-cost sources of good customers a small business has - built not on a marketing budget but on the simple recognition that the business next door is often an ally, not an enemy.