What is the best way for a cannabis start up to raise capital? Do you see any prospects in a new way to raise capital through Initial Coin Offering (ICO) in a crypto industry?

There are no "one size fits all" capital raises.  You need to have a plan for how much capital is needed, how it is to be deployed and how much of the company are you willing to give for the raise.  My advice is to sit down and come up with your business plan and then you can better determine the best way to raise capital for your individual endevour.
ICO's are risky.  In July 2017 the US Securities and Exchange Commission (SEC) claimed that coins are securities and therefore fell under their jurisdiction.  I do not recommend that any cannabis business employ any organization that would put them under the jurisdiction of the SEC.