I would like to know how to go about fiberglassing over steel .

I have some steel brackets flat bar 50 x 8mm very clean all millscale off ,is it best to paint the steel ? before fiberglassing over the top ? get the brakets plated ?? I would like what I am doing to last for years .

moisture wont get through f/glass (otherwise boats and surfboards would sink) so i cant see why you couldnt f/glass straight over the steel.

Not quite correct about fibreglass and moisture. Only the gelcoat (coloured surface) is non porous on a boat, hence problems with osmosis where moisture causes the glass to blister. But boats are polyester resin which is not 100% moisture proof.
However epoxy resin is water proof, but needs to be overcoated as it is not UV proof.

mmmm in short it is not a good idea...

Just gal dip them ...

I was going to make them out of 316 stainless but steel was close at the time I will get them hot diped gal .