I've been doing graphic design and p.r. work for more than 30 years. Believe me when I tell you this. Buying software and thinking it will make you a graphic designer is the same as buying a hammer and thinking it will make you a carpenter. You can't buy design skills in a box.
So take some courses. Read some trade publications. Apprentice yourself to a working designer (agencies love extra help.) Start a box full of printed samples of things you like, and ask a commercial printer and/or graphic designer how that was designed.
Good design: The ideas must come first. The computer is just a tool to help you make your ideas happen.
Bad design: Letting the software dictate the design. Newbies and unprofessional types get blindsided by all the bells & whistles in the software and forget their concept/message.
The most popular current software: Adobe InDesign (page layout), Illustrator (drawing/illustrating) and PhotoShop (image editing & manipulation). These are expensive programs. Every few years, a new program comes along that you will have to learn, but your basic design skills will not change.