Once you've assessed the risks and decided that there's no reason not to make a flight, you should continuously perceive, process information and perform based on the most conservative action. Using CARE you can consider the Consequences of the situation (weather, headwinds, fuel, etc.), determine what Alternatives are available (a different route, a precautionary landing, etc.), accept the Reality of the situation and deal with the External pressures. If the idea of developing personal minimums by filling out a form feels a bit like a homework assignment, Parsons offers an easier method in a recent article in the FAA Aviation News. She suggests you consider the lowest IFR conditions you have comfortably, recently and regularly experienced and set those as your minimums. It's not how low you've gone but how low you've gone comfortably. Be honest!