I think training is a must before you start - atleast to identify fabrics and know of some of the things to avoid at first.
Then do work for friends/family - get use to the tools, learn how to do things efficiently.
Study the forums or Facebook groups - the forums have great historical information, the Facebook Groups are maybe now a bit busier - and ask questions.
Then when you've done some hours, go back on another training course again - now with the experience under your belt you will take on much more, understand more and ask questions you need answers for for the job now you've experienced it. See through the Suppliers pushing products, they all have to make a living - just choose who you use based on what you want to use, their location and how you get on with them. A lot of products sold to us are rebadged for us and sold at a premium - you'll spot that as you go, just buy wisely - at the end of the day we all need the Suppliers, its up to you to not get bent over and shafted!!!