The main man for tutorials is Jerry Hatfield in the USA.
He has produced an amazing collection of Tutorials that he sells on his site SGDV
He also has a YouTube channel Jerry on YouTube
Jerry works closely with David Vincent Clarke in the UK.
David has quite a few tutorials of his own and also sells Jerry’s tutorials in the UK.
You can find David at Vistitle on DVCTraining
Personally, after having only tried Vistitle for a few weeks, the tutorials are a must!
Without them you will find it difficult to get started understanding the may finnesser in Vistitle.
Totally it looks like a lot of money. But compared to the alternatives it is quite reasonable.