Saag is one of my favorite dishes to make because it's so easy and adaptable and a great way to eat a lot of greens! I use a very basic approach. If you want a more refined version my sister-in-law (who is one of the best cooks I know) check out this link.
For my basic version, I chop onions or garlic or both. Have them ready, but separated. Start cooking the spices first, in a couple tablespoons of oil. Fresh ginger, ground turmeric, cumin, coriander. (I hear fenugreek is good too, but I actually haven't done that one yet. Maybe tonight!)
After about a minute, add onions. Cook about 5-10 minutes. If it looks like the spices are starting to burn, add just enough water that they don't burn. Add garlic and greens at the same time. This is the best part. You can use ANY kinds of greens you want. At least two bunches, up to five. Be sure the greens are chopped very, very small. Salt to taste.
Cook 10-20 minutes. Add chickpeas, potatoes, chicken, tofu or paneer (choose one). Serve over rice.
Here's another great meal to try Cajun Baked Tofu with Braised Collards and Grits: