My wife and I live in a one-bedroom apartment. We have 3 cats, so it is hard to grow anything indoors. My wife, with me glad to help, is trying container gardening. With the landlady's pleased consent, she has placed several large flowerpots outside, planted with a variety of vegetables and has cleared trash and weeds from near the garbage dumpster, made a compost bin out of pallets, and made a pie pumpkin bed out of a partially buried pallet. If you don't have cats, you also could plant vegetables in a windowsill planter.
Indoors, consider growing sprouts and herbs, such as basil. I've read that another possibility is mushrooms. Grow aloe vera for burns.
Ask around if your neighborhood has a community garden.
For lots more ideas pertaining to your question, ask Google, YouTube, and Pinterest.
Also, Google on:
guinea pig Ecuador
if you're not vegetarian or vegan.
for one way to save on cooking fuel costs.
If you live where there are lakes or rivers, get a fishing license.