I think cell culture can be one of the most exacting skill sets in biotechnology. I have done it, and sometimes it went well, and sometimes it did not! Millipore Sigma has posted some terrific (and free!) videos on their website that cover many important topics about cell culture. Some of the videos are very short, and cover just one specific point such as how to cryopreserve your cells. Others are webinars that are about an hour long and cover a number of topics including the incredibly important topic of cell line verification. I particularly liked the webinar entitled "How to Choose the Right Cell LIne for your Research". That really is one of the first crucial steps to overall success! Another one that I thought is very interesting is "Cell Culture in 3D Systems; Moving from a 2D to a 3D Environment". Some of the videos required a BrightTALK account but that was not hard to set up. If you are thinking about going into the cell culture field, or if you are already there and want to learn more, check them out!