I'd recommend a block heater if:
1.) your car sits outside during the winter, and
2.) temperatures are consistently below freezing.
I've seen several brands (I had one for my Bug when I lived in Illinois). Most basically bolt on somewhere on the oil pan or near the bottom of the block. Some are even designed to replace the oil dipstick when parked. You need to be near an electrical outlet of course, because it is essentially a heating element for your engine oil.
It's a whole lot easier to start your car when your oil isn't the consistency of cold maple syrup.
BTW, before I bought the block heater, I used a workshop light, and dangled it in an open area of the engine compartment. This worked well, but I feared the potential fire that could possibly occur.
I don't know if it gets as cold where you are as it does in Minnesota, but when my brother lived there, all of the apartment parking lot spaces had electrial outlet posts to plug in block heaters. He remembers it getting down to -60F some nights!!!
2009 ML350 (84K) - Family vehicle
2001 CLK430 Cabriolet (71K) - Wife's car
2005 BMW 645CI (124K) - My daily driver
2012 Mustang V6 (60K) - Daughter's car