Pick something relatively easy to grow (tomatoes are pretty straightforward in many places), and just try to get produce from it.

Once you have a result, then you can look at improving your approach.

No point running before you can walk, you're only going to be able to learn so much without actually trying stuff. Plus, if you already have soil to put stuff in, you're starting out better than I did. My stuff is growing in pots.

You're getting a bit late in the year to maximise most crops (if northern hemisphere) but that doesn't mean there's no point, so just throw shit at the wall to see what sticks. Seeds are cheap, and failed plants can still make compost as well as provide a learning opportunity