Easiest first step would be to put your shovel into the grass and remove the turf/grass layer.

Then dig around a few inches into the soil underneath and see what kind of soil you have below that. If it's hard or very compacted you can figure out if you want to till it with an amendment or invest in raised beds. If it's easy or moderately easy to work with you can skip on the raised beds unless you really want to use them.

Since it's a new garden I'd highly suggest getting a soil test done. Every state has a lab(s) to test soil with some very high end equipment. They tell you what the results mean and what you should add to your soil to get it in optimal working shape. This isn't necessary and many people get away with not bothering with it, but I'm a huge fan of them for a soil you're not sure of. Avoid the do-it-yourself-at-home kits. Most cost as much as a professional soil test in most areas, anyway.

Raised beds with cardboard or layers of newspaper to kill the grass underneath are the easiest IMHO.

I agree with the gurler, lasgna gardening is the way to go IMO. I have a friend who always tills and gardens in rows the traditional way and he always offers to till mine, but I politely refuse. Every year, he is overrun with weeds, has to water LOTS more and never gets as much from his garden as I do. That being said, he does raise some yummy sweet corn! I have pretty much given up on it since it's hard to do in small raised beds. Do whatever feels comfortable to you. Plants don't care where they grow or what the garden looks like as long as they have room to grow, sunshine and food. You will find as many different methods to gardening as there are gardeners. Happy gardening!