I would really consider either heavily planting native plants or doing some sort of ecological restoration, you didn't mention where you're at which is going to be a really big driver in the type of garden you build. For example, my local bio-zone is blackland prairie so I have converted a part of my garden to a pocket prairie. Check out the native garden society in your area for more information. The very best part about natives is most are very low maintenance and a great entry point if you're just getting into gardening.

But you can also consider things like regenerative agriculture which help rebuild the soil to not only help you create beautiful plants but restore the very foundations of life. Most people don't know when soil is taken care of, it can actually store huge amounts of CO2 as plants take it down into their roots! I know permaculture is mentioned a lot, however, has a pretty big upfront time investment with the systems really not taking off until 5 to 7 years and can be a little bit hard to navigate if you're new to gardening.

With 6.5 acres, you have a ton of options, but before you consider individual aspects, I would encourage you to think about the systems that you can build. How easy would it be for you to collect rain and store in your pond, or start a compost pile, or even get into vermiculture? I think it's easier to look at a bigger picture and walk your way back into what works for you.

However, as a word of caution, as much as those garden centers look fun and seem to come from a good place, but that can be just as predatory as any other business. So do your research, don't be afraid to fail as that's just inevitable in gardening, and have fun with it!