Questions about filing sales tax with an online retail business based in state without sales tax

I have an online shop and up until now I have only sold with ebay and Etsy who handle all state sales tax (collection and remittance). I want to have a standalone online shop and I have a few questions about how I handle state sales tax.

 

  • I am only selling from a state that does not have sales tax (NH). What does this mean for me? I do not have a very high volume of sales at this point
  • I have heard I need to have "nexus" in a state before I even have to worry about submitting/filing anything. Is that true? If so, what are those thresholds? 
  • If I do need to file sales tax for independent states, how and at what frequency do I do this? 

 

Appreciate any other info that might be important. Thanks!