At that size start with loppers/shears or a machete and cut all the stems/trunks/brambles/etc. If you have any big ones, come back with a saw.
The followup work may go better if you divide the ground up into a grid of manageable size blocks - it's more humanly possible to clear out a 3x3 or 4x4 foot block than it is to attack the whole backyard, even if the whole backyard is only 20x20 feet or so. Do one, and stop, or two or three, whatever works - it just makes the progress more visible to you doing it.
With saplings in play, a mattock and/or pick will be useful to get the roots out and break up the uneven soil. You might also need to dig out rocks, or dig holes to drop rocks into, below the surface. A good quality stone rake (also called a bow rake, evidently) (which might or might not be what your "iron rake" was referring to) will help to even the soil once the obstacles are removed from it. Things move differently if you use the straight back of the rake and the toothed side of the rake, both can be useful.
You might need to shop somewhere that does not only have the cheapest hand tools China will shovel into a container to get a good one. Or try someplace with used tools available to find old ones that were made better.