If I do voiceover work on the side and my "assets" include my laptop and a microphone, do I need to fill out my state Tangible Property Tax Return in state taxes?

Which state do you live in?  Generally, a laptop would be an asset and a microphone would depend. 

Florida!

There is a $25K exemption for assets, so no, you probably do not need to file the tangible tax form (DR-405).