Scotch goring gambit

I'm studying so many things and *thought* I knew opening basics until I was swept twice by this opening. It seems if I am not in a Ruy Lopez type closed center then I'm lost. When presented with something like the scotch, at the point of the gambit challenge, what should be going through my mind? I know accept or not accept, but what else? It seems as black I was doomed as soon as the gambit challenge. Silman would highlight that my amatuer mind panicked in both games. They say newbies should not memorize openings, but how best do you play an opening that you never have done? I need to get past this opening plague lol

There is a nice explanation here:

http://en.wikipedia.org/wiki/Scotch_Game#G.C3.B6ring_Gambit

and the statistics from chessgames.com opening explorer:

4...dxc3	403	53.3% 16.1 30.5%
4...d5	274	38% 32.8% 29.2%
4...Nf6	99	38.4% 33.3% 28.3%
4...d3	81	29.6% 35.8% 34.6%