Just decide what sort of exercises you want to do and from there you can determine what equipment you should need. Not everyone needs the same equipment. At the very least, I recommend a bench, a set of dumbbells (or a multi-selector dumbbell), and some general cardio equipment (jump rope, plyo box, etc).
Many people can get results w/very little in the way of equipment. You can do a lot w/just dumbbells for instance. I sold my bench a while ago so last spring I used dumbbells and a barbell in the garage. Nothing bigger than 15 pound weights, did benches off the floor using crates and for cheating deadlifts. Then did chinups using both grips by placing the bar across 2 6' ladders. Situps and other calisthenics and running or biking. Not as effective as in the gym but helped. If you "google" you should find guys that made some machines using pulleys and cables. Not too hard. Easier to find a bench and focus on bench, squat and deadlift but again, as deadlyapp states: all depends on what you're training for. Good luck.
I have some dumbbells, a makeshift pulldown affair using a chinup bar and stretch banding material I was Rxed for physical therapy. Got a bike trainer, but took my bike off it to use in the street again and got a Concept2 Model D Rowing Machine, basically so I could get aerobic indoors (having developed knee pain from running up and down stairs!!!).
But what I'm doing "religiously" is skating the street 6 miles/day, when the weather permits (which has been a lot, it being a severe drought year here!!). That by itself has me in great shape... well, good shape.