Here's my list of favorite art supplies for painting in acrylics:
1. Paint: My favorite kind of paint and the best quality out there is Golden. The investment is WORTH IT! If you are just painting for fun, I recommend starting with a student brand paint, like the Basics line available through Liquitex.
2. Art Supply Stores: My favorite art supply stores are Artist and Craftsman and Blick online. Both have AMAZING deals and I usually shop when there are great discounts to help save some money. Also, I secretly love trolling the aisles of A&C and just touching and smelling all of the art supplies. :)
3. Brushes: I paint with Acrylic paints and I love to use a variety of brushes for my work. This choice is completely based on preference. I prefer to use flat brushes with strong bristles, as I apply the paints in a thicker, more "impasto" manner most of the time. I like to use both synthetic and natural haired brushes, but I can offer the suggestion that it is worth pulling on the fibers a bit at the store to see if hairs fall off. I HATE when there are rogue hairs in my paintings after the fact. Insider secret: Ikea's kid department has AWESOME brushes.
4. Canvas vs. Paper vs. Birch Board: This age-old debate (Actually, I guess the oldest debate was just stone, but I digress) is really 100% based on textural preference. Most artists are really tactile people, so we all have our crazy idiosyncrasies based on them. I am a canvas and paper girl for no other reason than just because "I like them"!
5. Oil vs. Watercolor vs. Acrylic: Again, this choice is totally personality-based. I LOVE acrylics because they literally match my personality. I am quick, cheerful, bright, and stubborn. We work well together. Oil painting requires a bit more technique and ventilation as well as A LOT of patience (which is not my area of expertise!). Watercolors are free-flowing and require a bit more control, but are LOTs of fun. So, basically, just start experimenting and see what you enjoy the most.