If you have never taken a class, then taking classes at Michael's would be a good place to start. They are inexpensive enough and even if you only learned a few new techniques, they are well worth the money.
I started cake decorating basically when my children were young...some 35 years ago....just teaching myself from books. Then I stopped after I had to return to the workforce. A year ago, I decided I wanted to get back into it, just as a hobby, but things were so different (fondant
what was that?) so I took all the classes I could at Michael's as well as watching all the youtube videos I could. Something they didn't have way back 35 years ago. Plus the things that I have learned on this site from fellow CC'ers has been amazing!
I don't say I'm a great cake decorator by any means, but I enjoy it and anytime I can learn something new from someone who knows the proper way to do it, I'm there! My Wilton instructor was amazing and I still keep in touch with her if I run into any problems. I have started taking more specialized classes now and in a couple of weeks I am excited to be taking an airbrushing class.
It is true, as Kakeladi stated, they will try to push the Wilton products and some I've bought and others I passed on or found a different brand that was recommeneded by other cake artists. For each class, there is a student kit that you need to purchase, but with the Michael's coupons, they are not that expensive.
So, in a nutshell...my advice would be to go for it! Good luck!