What is a 'Non relevant sub topic'?
This sounds serious!!It can be.
You need to keep your sub topics relevant to the Main topic.
It can be about you but...
Example - One of your sub topics could be about you Travelling in Europe and how you got to those destinations, the culture difference, the food etc etc.
BUT NOT..
Sub topic 1 - We went to Lanzarote, it was hot and nice with beautiful scenery
Sub topic 2 - My partner and I went skiing in Austria I got very drunk.
Sub topic 3 - We went camping in Croatia, it was hot and nice with beautiful scenery ...again