Here is a forum that deals with living on board. They can probably answer your questions or already have. You might have a lot of catch up reading to do. Living Aboard Forums

If you are thinking of using a windmill you will want to use a Savonius type rotor. This is a vertical axis style rather than a bladed one. Meaning less interference with the sails. I've posted several links on this thread. Vertical Axis Wind Turbines

Fresh water will always be one of the critical factors. A rain catchment system is a very good idea. But then again you can never count on rain when you need it.

Whether you are using a solar distiller or a reverse osmosis system to purify water. be very careful of the water you start with. They might work fine on normal seawater. But may be overwhelmed by a spill or dump from other shipping. And never take in ocean water while in port. It will probably be a real witches brew. You will most likely poison yourself and destroy your filter.

Use any and all strategies to reduce your power consumption. Such as already mentioned LED lighting.

Also consider an alternate power source. I.e. a portable generator. Yes many boats have an auxiliary engine that can also generate electricity. But you want a back up. You may need to power a radio to yell for help and your kicker is dead. This could be a commercial genny. Or a homebuilt 12 volt. It would be made from a lawn mower engine and a car alternator to charge your battery bank.

Make sure you have waterproof storage for everything not actually in use. Even double protection if possible. Bucketed or boxed with bags inside. Flooding even minor is not only possible but very likely.