How can I cross-promote with other Lagos businesses for free marketing?

Identify non-competing but related businesses in Lagos (for example, if you do cakes, partner with event planners).

 Propose mutual shout-outs: on social media, email lists, stories.

 You could host joint giveaways (each brings audience). 

Swap guest posts or features in newsletters. Bundle services or products (you refer their clients, they refer yours). 

Host a small local event or online workshop together, each promoting to own list. 

Since both have Lagos audiences, shared exposure helps both. 

For new or small players, such collaborations cost nothing (just effort) and are often more trusted by local audiences. 

This is a question likely asked by people trying to grow via partnerships locally.