Hi Hoo: The answer is "very slowly"! Take a good look at the area and decide what you want to keep and what you want to get rid of and how you want it to look. Then, starting in one area, work your way in, trimming, digging out, moving and throwing away. Just like cleaning your closets. Slow and steady wins the race. It will take a while but you will be happy with the results. Good luck and keep a towel handy to wipe away the sweat:)
Cut it down with a weed eater, mower, or other cutting device.
You've got your work cut out for you !!!
Here's a cute little video that might help you inspired...
Cut out all plants that you do not want and then trim the others. If you have a lawn, raise the blades on your mower and cut it down and then cut again to a height of 3 inches.
If you're in a rush, spray Brush Killer in the area, but do not let it 'drift"!. Once weeds are dead, rototill if possible, adding soil amendments as needed. Put down Preen granules to kill new weeds. Plant established plants (seeds and young growth will not withstand Preen). Fertilize, mulch, and scatter more Preen granules atop mulch.