the best mechanical advantage i've found for hauling the mainsail singlehanded was this: i put some 3M non-skid strips on the curved portion of the coaming just below the right-hand-side of the house top. then i stand back a little, put my right foot on the non-skid and then pull away! when pulling, my body is tilted a little back. that way, i can exert maximum pulling power on the main halyard, and also look at how close the head-board was to the mast top.
for the furling jib: i have fitted a jam cleat on a 1-inch raised platform at a point just before the furling line goes round its own cleat. that way, i can either pull and rest and pull, or i can put the line on the winch and grind away in a blow.
in light winds (< 8 knots?), the main usually got caught on the staysail when tack/gybing. have to got forward to free it and put it onto the other side. if staysail is not your staple, store it away.