Before anything else, in order to have a career in design, you must have a desire and passion for creating artwork. Art is everywhere you look, it is a word that spans out to a broad range of things, it can mean building a house, drawing a portrait of someone, producing an advertisement, drawing out how an aircraft will look, and an endless amount of things. It's just how you perceive it as. As for design, consider it to be a subcategory under art. When designing something, you can either take a concept or idea of how it is supposed to look and produce a sketch or diagram of how it will look or it can be taking something for what it is, in its simplest form, and making it more appealing to the eye, beautifying it.
Now, to begin a career in design, you must be ready for brainstorming ideas, creativity, deadlines and sometimes even creating things you might find to look terrible but if that is what the client wants then you are just there to please them!
A career in the design industry consists of being able to use and keep up with various design programs and letting the creative juices flow. It does not necessarily require a college degree but that would help you a lot in finding a job in the field. If you were looking to go to a school for design, you might want to consider taking courses related to illustration, digital media, graphic design, computer animation, and many more. The courses you take will also depend on the type of design you would like to get into.
Let's say you've got the desire, the passion, and the skills down, now you just need to get the creativity flowing and start a portfolio in order to show what you are capable of doing so you can begin getting paid for something you love and want to do! This might sound easy to you, but it requires a bit more work than you might think.
Producing a portfolio for a career in design can take a lifetime. This does not mean you will never find work in the field though. People in the design industry are constantly adding things to their portfolio to show their achievements and their design capabilities.
Once you feel comfortable with your skill capacity, get out there and show off your portfolio and begin your career in design!