Don't trust forecasts - the only one I'll guarantee is for a flight I completed ten minutes ago.
Just because someone else got through doesn't mean you can or should attempt it.
Listen to your gut - use plan B, C, D or E early.
When you use a backup plan, create a replacement backup plan.
When there are two things causing you concern (ie minimum fuel, average weather, approaching last light) be extremely cautious.
A superior pilot uses his/her superior judgment to avoid having to use his/her superior skill.
Its much better to be on the ground wishing you were flying than to be flying wishing you were on the ground.
PS Sniffing fuel is not foolproof either - fuel drainers can take on a strong fuel smell. A good cheap, quick and easy way to check fuel for water is to add known water to the sample - if you don't see the phase change then it is all water.