Hi Javacentral,
I don't have the universal formula, but let me explain how I see this:
Step 1. We exchange Youtube Analytics Data as screenshots;/access/videoconference
Step 2. Based on the number of views, audience data we can reach an agreement about details.
Step 3. Yes, on the end screen tab of video we just paste the links to each other
Step 4. Based on efficiency, we decide to continue this cross promotion or not.
Your Channel/Video number is too small at the moment for this type of collaboration with me. I am looking for somebody, who have a similar audience(75% and more is the male audience) and have monthly video or at least channel views on the level between 300 000 and 4 000 000 monthly views. Same time I wish you good luck and every success, your videos are really interesting, one day you should find your audience!