Wind/weather and Tide are obviously very important variables. Quite a few marks that I fish will be unfishable with certain wind directions and tides - either too rough or the water visibility will be like coffee. Lots of rain in the days before can color up the water too from run off so I tend to avoid estuaries after heavy rain. We have big tides here and big spring tides can colour up the water too, even in calm conditions. Checking webcams near these areas can save wasted trips. But nothing beats experience and keeping a fishing logs.