Help, I need somebody

My boyfriend told me that his grandma wanted me to do an art piece in memoriam for her late husband. I mean it's really cool that I'm being commissioned finally but this is a big deal. Usually it would be something like drawing a mermaid or something cute like kawaii girls and tumblr stuff. Now I'm kind of afraid like I'm going to mess it up because I utterly adored his grandfather so it's difficult.  I am still going to take the commission but I just really hope I can do this right and step put of my own comfort zone to make this happen and do it exceedingly well.