What am I allowed to offer to my potential customers?

Anything connected with video design, free templates packs from my site, scripts, presets if they purchase my items? Anything that is not connected with it like sound fx, 3d models? I’ve seen some authors are offering free customization of a template if it is purchased, is it different from offering free stuff?

Neither is allowed.

I’m sure some authors try it but it’s not very clever given it breaks the agreements.

Thank you!