Well first of all you are going to have to pick the right kinds of materials such as brushes, paints, stretched canvas etc. You need to buy the right kind of materials and also the best kind of materials. Then you have to buy brushes. Choose brushes that are suitable for acrylic paint, they should be either flat or round. Try buying brushes with natural hair, they will do much better in the long run and they will not leave bristles on the canvas. Look around and see if you can find good bargains in your local art supplier store. Again if you don't know what your art supplier store is, just Google Michael's or Joanne and check out their nearest location to your zip code. If you need inspiration or want to look at some sort of example of acrylic or oil art, check out paintings of flowers, abstract art, landscape and fantasy fineart, etc.
Okay now buy some acrylic paints, you also need to know your color wheel generally well before you start. Just know your basics such as yellow and blue make green etc. and you can figure out the rest by doing. Experimenting with colors will take a while but your results will be great in the end. Use good quality paints so the colors on your artwork will be vibrant. Also choose a good canvas. If you want a good piece or art you should probably try and find a stretched canvas that will maintain its look. You can also learn to stretch your own canvas, but that's a huge hassle so just buy one from the store (they're not that expensive especially if you find a good sale).
Decide what to paint. This is the most important part of the process. Again check out the type of original fine art that you like. For inspiration you can also look at some Contemporary Abstract Art Prints. Find a bright place with natural light. It should be somewhere in the basement or outside, a place that you are willing to get messy in. If not put newspapers on the ground but again my suggestion is using a place that you don't mind getting dirty because accidents always happen. Also get a palette or a paper plate (the cheaper way) to mix all your colors as you paint. It's much better to mix them on the plate before you put them on the canvas. Sketch basic main parts of the art work you are thinking of creating. Also start with your background first, paint your sky, wood, fields first before you concentrate on the details (back to front technique). Wait a while for those to dry a bit and then begin on the details (acrylic paints dry much faster than oil). In the end make sure you clean your brushes right away! If not the paint will dry and destroy those brushes.
These are first steps in the journey of painting Abstract ART with acrylic!