If you want a really solid, structured course, Udemy has a lot of really good video coursewares that are all at-your-own-pace. This one looks pretty great and starts you from the very basics if you don't have experience with programming previously.

(If the price seems a bit high, sign up for Udemy, ♥ the course, and within a few hours it magically goes on sale for like 80% off. They're aggressive and automatic with their discounting)

https://learn.unity.com :P

Best advice i can give is:

• if you don t have a programming bg, learn the basics and OOP. If yes:
• after finishing learnunity series, start testing yourself by solving incremental problems (e.g, increase the complexity of the task each time)
• nothing beats practice. For the sources, catlike coding. Skip videos as most of them are fragmented, but i suggest the early videos of Sebastian Lague.