How should I effectively use electronics to fish in Florida? Other than a depth finder, are they really even needed in most applications?

Sorry, new boater and thus far I have had a lot more luck on the shore.

That depends on the lake you are fishing on. There are deep lakes here in FL, that utilizing electronics properly will help you ID brush piles, shell beds, and bait balls. There are other lakes where GPS will be more important... lol 

Not so important in south Florida.  Most of our lakes down HERE are shallow and full of vegetation.  The bass are hanging among the weeds most of the time in 3 or 4 feet of water.  The canals are pretty uniform all similar depths except for a few holes.  The deep holes are often void of O2. therefore few fish.  I do fish drop offs in the canals but you don't need electronics to find them, and they are next to thick vegetation.  The O2 is where the vegetation is, bait fish where the vegetation is, bugs, snakes, gators, frogs, are where the vegetation is found.  More food in the vegetation then anywhere else.  The shade from the hot Florida sun is where the vegetation is.  Its totally different then fishing northern lakes, and reservoirs with loads of structure.  Heavy line, reaction bites, and fishing back in the junk, that's what it is all about.  Go further north and you'll find different situations, where electronics can play a bigger roll.  I do like electronics, to check the water temps, look for thermocline depth, and to find my way back home when it starts getting dark.