For as long as I can remember I have enjoyed art. First starting out with crayons, markers, and those cheap watercolor sets you have to buy in elementary school. My high-school art teacher said the best thing you can do for a young kid is give them blank scratch paper to draw and color on versus a coloring book. The blank paper gives them the freedom to do whatever they want and really will help them use their imagination going forward.
For the majority of my painting/art career I would always sketch out my work/design ahead of time. I definitely recommend investing in a sketch pad and an assortment of pencils. Nice thing about drawing is it takes minimal supplies and can travel anywhere with you very easily. I've drawn many pictures on airplane rides. It's a great way to pass the time and hone in your skills. Plus the flight attendants and other passengers often have commented when they see me drawing.
Other than practice the biggest thing you can do to help yourself have the best chance of success is invest in good paint brushes and good paint. The flimsy nylon brushes will do nothing but let you down. You need a good stiff, natural haired bristled brush. If you're going to try and create the Bob Ross paintings I definitely recommend you get some of his brushes (oval, round, and blender). Otherwise you just won't get the same effects Bob does. And as he often says, "then you'll be mad at me. And we don't want that."
Once you have the brushes then it's time to get yourself some paint. My entire art career I've used acrylics. Only recently did I change over to oils. For acrylics the best brands I've found are Utrecht and Golden. They are nice and firm. Stay clear of the cheap kind you'll find in the small bottles at Hobby Lobby or Michael's. Those are meant for ceramics and you will definitely struggle if you try to paint with them.
If you're going to paint with oils I recommend the Bob Ross brand. I'm sure other brands would probably work just fine. I just know that Bob's paints work fantastic for his wet on wet method. They are nice and firm (which you need) and price wise I think they're on par with other brands. I usually buy the larger tubes on Amazon which run about $17-$20 a tube. However, the large tubes last for quite a while. Especially if you don't paint all that often.
Lastly, have fun when you're creating art. It's one of the very few things in life I do where I have zero worries. Happy painting