Presuming that you have checked you don't have the usual problems with Fs ie the reflective coating has dulled/disappeared behind the bulb, and/or the glass internal lens is fogged over, then fit some uprated quality bulbs such as osram nightbreakers. These bulbs are legal(55w) but put out about twice as much light as a standard 55w bulb. I have them in my F and the dipped headlights are fine.
Don't be tempted by ebay 'super bright' type cheap bulbs or increased wattage ie 100watt bulbs. The former are rubbish, the latter are illegal and could cause issues with melted electricals.