Choose the north-eastern silk stall. Stand between the stall and the building, as if you were the stall holder. Kill the guard that patrols behind the silk stall and the silver stall. Start stealing silk. Watch out for the knights of Ardougne and the other guards. Don't mind the hero in blue or the paladin. They can be standing right next to you when you're stealing, but don't do anything unless your combat level is near theirs. Every time the guard behind you reappears, kill him and continue stealing.