Self suffiency in this age seems like an outdated idea. Our next meal is often in our refrigerator, seldom farther away than the next restaurant or grocery store. "Smart" hubs turn the heat and/or AC off and on at appropriate times, if not, we do it ourselves.We flip a switch and lights come on.
We get so used to things being easy that it can be a shock when they aren't.
A little self sufficiency might not change those things but it can make life more liveable when things don't work right, and it can be a money saver. Besides that, it can make you feel good. Having back up plans for when the grid fails us, even for a few hours, can make things a lot easier.
A lot of the things our grandparents used are logical choices for today, but there are some new (or renewed) methods that we could use, too.
For instance, kerosene lamps or lanterns and candles can give you hours of light when the electricity goes off. So can a solar powered flashlight or stand alone light. There are light bulbs now that work on electricity but store it in batteries so when the power goes out, they continue to work for some time. There are flashlights that you crank to charge the battery.
It's a good idea to invest in more than one of these technologies. None of them are expensive. I have found kerosene lamps in thrift stores for almost nothing. Candles are often cheap, but be careful of what kind you buy. Some will hardly burn because of cheap wax.
To be very frugal, use kerosene instead of lamp oil. It's quite a bit cheaper and it stores just as well. It does smell like kerosene, but it's not all that unpleasant. Be sure of your candles. Beeswax or soy are best for air quality as well as light, but the wick has a lot to do with it, too. If you're not sure, try out a few before stocking up.
Solar or wind up flash lights are not expensive and handy to have anyway, but they may not be as bright as battery operated ones, so be prepared for that. If you use them, you don't have to buy batteries at all. Maybe a good compromise would be to have rechargeable batteries and a solar charger. You will need to keep the batteries well charged all the time, just in case.
The new kid on the block, the light bulbs that work just like light bulbs during "normal" times, charge a battery while it's working, so when the electricity goes off, the light bulb will switch over to the battery and continue to shine. There is a time limit on the battery, so check that before deciding to rely on them.
Taking it a step further, you could make it a practice to rely on lighting without electricity. It won't take many evenings to discover the best practices for light. Your own home and preferences will make a difference.
It's wise to try things out before it's necessary. That way, you will know what to do and what to expect and that makes everything easier.