I'll second Alchemeys post. Get a modern panel, preferably with a couple of cigarette lighter sockets. The portable fridges, hand held VHS radios, cellphones, etc etc all will have an adapter for those 12v sockets. Go LED
lighting inside right away and later outside. Plan ahead, spare breaker for fixed
radio, one for a spreader light, one for
depth finder, V-berth fan and so on. Figure out where you'll connect in a
solar panel, 80-100Watts would be fine. And buy the proper
marine wire for your runs. The heavy high
current runs are only needed to feed the starter. Use the both/2/1/none switch to select starter battery. A house battery and a starting battery are sufficient initially. Add another house battery if needed. My panel is wired/fused to the house battery, and is powered directly from it. As long as the main switch is never set to "both" I don't kill the starting battery. I can't access the starter battery to power the house otherwise. I never use the "both" selection as it will pull down the rpms on my little 9hp
Yanmar diesel enough to notice at idle. Amazon has Perko and Blue Sea selectors if needed. And
panels.