How do I start a vegetable garden from scratch?

The sun talk is right, but what they don't tell you is you need to do a water test before you even start. Dig a hole, pour some water in it and see how the drainage handles it. If the water sits there for more than an hour, you've got a serious problem and you'll either need to raise the ground level or do something more drastic. I've had the experience of digging in spots that looked perfect and then finding an impermeable clay layer underneath. Now I always do this test.

On the soil side, yeah compost and mature manure are essential, but I'd also throw in a ton of sand if your soil is too compact. You don't need to do some complicated chemical analysis, just feel the soil between your fingers: if after rain it turns into a mud ball that doesn't crumble apart, you need better drainage. Add 10-15 cm of good compost, mix it well for at least the first 30 cm deep and you've already done 70% of the work.

Here's my practical tip that saves lives: start small, really small. Don't make a huge garden because then you'll get bored in August and end up with a field of weeds. Start with 4-5 square meters max, plant easy stuff (tomatoes, zucchini, salad), see how it goes, and next year you expand. Trust me, it's the best way to learn without stressing yourself out and without dropping a fortune on tools you'll never use.