You said "clear out all this" so can we assume you aren't planning to do only a few dozen square feet at a time, but all of it as one batch?

The easiest way, as far as sweat goes, would seem to me to be: mow and smother. There are a lot of options for both those parts. Cardboard is involved. Lots of cardboard that will rot down in its own good time.

Dig (if you must) next year.

Depends on what type of grass that is, and what other types of weeds might be in there. Also, what is your timeline for getting it planted, what sort of tools do you have access to, and how much do you want to clear out.

I have done this many times:

Mow the grass area with a mulching deck. Wait for a couple days until the clippings turn yellow. Dig the bed, single or double digging. Either bury the grass roots, or expose the roots to the sun and do not let the roots get water. This way, you try to kill all the perennial grass.

Do not worry about grass seeds. There are many many seeds in the soil anyway. Use mulch to manage the seeds in the soil.

Wait a week or two, continue to kill the perennial grass/weeds. Amend the soil if you can.

The garden should be ready when most of the perennial weeds are killed.

I need it all cleared out to prepare for next year's garden. The only problem is this area is not level. It appears that someone did raised rows. With a tiered effect. I weed whacked all the tall grass. Would covering with cardboard over the winter work in time for a spring planting?

You can certainly do 2-3 tiers. Use some old railroad ties, or some bricks/stones.

Cardboard is too slow. You'll need to dig the bed as early as you can. You can even plant a cover crop, then till the soil. Let the bed sit over the winter, so all the grass roots get composted.

You can dig the bed in early spring, but the you may not have time to get all the grass roots composted.

I don't want it tiered, I started hand digging it with a shovel today, it's very labor intensive. Would a tiller make easy work of it?

If the slope is steep (looks like), then you'll have problem with watering. A tiller is good for a large area. It looks like your garden is small. A large shovel should just work fine. Wait until after some rain. Or it will be hard to dig.

I'll be very careful with the deep slope. It may be better to plant some fruit trees, instead of vege garden. You do not want any soil erosion.

Rent a small excavator and save your back. If you don't know how to run one, ask a friend or family member, or hire someone. Rental companies usually charge by the day, but that area is so small, I'd find a company that charges by the hour.
Good news is you will be killing two birds with one stone as you will not only clear the overgrown mess, but you will also be able to level it. If you are worried about the bushes (if you want to keep them), you can remove/re-plant them via excavator as well.

This post was edited by AuroraWA on Mon, Sep 8, 14 at 16:24

You might find turning it over with a fork or spade easier than a shovel.

Digging is hard work, but you will get to know the site and soil that way. BTW, I love tiered beds.

This early in the fall, I would throw cover crop seeds over the cultivated soil. Oats are great because they winterkill by January and become a winter-to-spring mulch. In spring you can rake away the oat debris and start planting.