Cleaning my old Singer sm

My poor ol' 1950 Singer 15-91 spent 3 years in the garage with Missouri's
heat and cold and high humidity. It has this thick, brown-ish colored,
sticky, greasy feeling film on it- it's much like the cooked-on grease you
sometimes see on the bottom of frying pans. Any thoughts on some thing safe
to clean it- that won't mess up the lovely decals or the black paint?

Also, I hear y'all talking about cleaning and lubing the old machines to get
them running well. Can somebody tell me *exactly* how to do it? Not just
'clean it well' but how do you get up into the innards, what do you use for
wiping and for removing the gunk, and how do you know if something up in
there needs help or special attention? What product do you use to lube it
and where? All the research I did some time ago really didn't say how to
get to the stuff- just a broad 'clean it' and 'lubricate it' statement. I
need very detailed specific instructions, please. Help?

Leslie & The Furbabies in MO