"TRYING FOR THE STRONGEST TINCTURE"
I think you are asking one of two things:
how to increase the strength of a DIY tincture, in which case the strength is typically related to the ratio of CBD to THC and the overall percentage per milligram. So, you add more or less of these elements.
Increasing dosage from a pre made product. In which case you would take more CBD in order to increase the strength.
This answer represents my opinion only. I hope this helps!