Depends on how fast you want the land cleared.
Quickest method but back breaking. Hand fork out all roots, and then plant. Check regularly for any bits of weed left which will grow and hand pull.
Quick method. spray everything with glyphosate. Fork out anything left after a month. you need a calm day to spray, and dry weather for 24 hours after.
Slow easy method. Cover everything with as much organic matter as you can get hold of. Farm yard manure, grass clippings, compost, sheets of cardboard, cover with thick black plastic or old synthetic carpet, and leave for a year and the worms will do it all for you. This method was used a lot at Ryton gardens when they first opened.