As a lefty myself i'd say try maybe opening up your stand a teeny bit....this works for me facing right handers and i see a lot of sucessful right handers do it against us lefties.
Were they swinging the ball? If it away swing i sometimes move a fair bit infront of the stumps knowing that anything pitching inline should miss and anything hitting may have pitched on leg unless very full. This becomes easier to work off your legs i find as well as moving yuorself nearer to the pitch if i wide line is taken by the bowler.
If inswing i find you have to wait for a bad ball, not found a sure fire way of playing this that i am comfortbale with, i usually look to get off strike by nicking a quick single, cant get out from the other end. But there are often a few tickles down the legside to be had off an inswinger.
As a bowler if you have no idea then we'd probably look to bowl straight, if you are a rh bowler and bowl to lefties its the same principle so have a think about that. The length, if bowling on a decent wicket, would probably be going through at around top of stumps. Its the same principles as normal bowling really mate, we arent so demonic that we've created new rules for our bowling