It's very difficult to learn to cast from getting advice over the internet from virtual strangers. Keep in mind there is no substitute for practice. Short practice sessions several times a week are better than one or two long sessions each week. In other words, it's better to practice ten minutes a day six times a week then once a week for an hour.
Stick with your plan of getting some reputable casting videos and committing to practice. Try to avoid the temptation of watching other people cast, especially in the beginning, unless that other person is a trusted pro.
Your other option would be to take some lessons from a professional or attend a casting school.