Open it up remove the recoil spring Assy. then the bbl. run a bronze brush with a good brand bbl. cleaner through the bbl. then follow with some cotton patchs till they come through clean then some quality gun oil on a patch.
I shoot some Breakfree CLP around the slide then using and old tooth brush give it a going over. Follow with some cotton swabs in the groves. Then start on the frame using some BF CLP again and the brush also the swabs. When done some gun oil here and there.
Making sure the recoil spring Assy. is centered on bbl. rack it back togather. Thats it.