A single piece of life-saving gardening advice

Sand. 

When you build your raised beds make the soil about 30% sand. This is because sandy soil is much easier to weed than any other type of soil, especially clay. I've probably spent a couple of thousand dollars setting up my garden and if I were doing it from scratch I would use tall galvanized steel containers with sandy soil. You can get the sand delivered by the square yard much cheaper than buying it.

You have to put enough sand. Not enough and the soil will actually become more compacted rather than less. Don't bother trying to use the dirt you have because it is full of weed seeds. Use a mix of potting soil, vermiculite, and sand with a sprinkle a fertilizer and azomite mixed in.

Sand, 1 half cubic foot bag

Potting soil, one 2 cubic foot bag (don't use miracle grow)

One 6 dollar bag of vermiculite, about 8 quarts

Handful of azomite 

Handful of fertilizer, doesn't matter if it's synthetic or not 

Sprinkle of lime

Mix in a wheelbarrow by hand and dump it in your raised beds. You can put logs in the bottom if you want it doesn't matter.