Consider you and your partner’s personal skills. Again the obvious ones include boatbuilding experience in any material. You may have obtained your boatbuilding experience by building and or fitting out your own boat. This is a factor worth considering when you are deciding how you will acquire your boat. The actual building and fitting out of a reasonable sized cruising boat will certainly add to your marketable skills. Most useful when you are cruising.
Most tradesmen have marketable skills, welders, metal workers, carpenters, plumbers and electricians will find part time employment not only ashore but among their less handy cruising contemporaries. If you have some experience with the maintenance and repair of electronic equipment you will be very much in demand.
Dentists, Doctors Chiropractors and other professionals can often earn worthwhile fees both ashore and among the cruising population. Some licensing requirements may interfere with your activities ashore but it is worth investigating in advance where you can legally practice. You may be able to obtain a licence in those areas you plan to visit. Language skills can be turned into cash as can secretarial experience. Computer literacy is a definite skill and one that will always find a ready market. Writing articles and perhaps a book on your experiences is another possibility; be aware that these latter activities are in a crowded market and are not that well paid.