This is the kind of "stuff" you should learn by doing! You are not going to do much harm to that pistol if you follow the advice already given on your other posts. Neglect and time had done the harm, now you can only improve it!
I already told you to take the grips off. Dunk the rest in the thin oil of your choice and let it soak.
If it will come apart easily, take it apart first. But be sure you know how to put it back together again.
Solvent (oil, wd 40, kerosene) won't take the bluing off, just don't use any acid (like vinegar), base(caustic soda or bleach), or naval jelly or coca-cola- they will remove any blue they touch.
Sometimes I take pictures of odd stuff, just in case I forget.
If the grip screws don't want to move, put a drop of penetrating oil on the inside and at the bottom where the screw head contacts the frame and let it soak a day or two; repeat if need be.