The problem with home baits, in marine environments, is the preference of marine fish. I think it fair to say that marine animals prefer mammalian remains to be soft and rotten!
(I once had the task of landing a drowned person from the sea. The first thing the professionals did was to shake the shrimps from her head, eyes and brain!)
So saying ground baiting might be an advantage in Mediterranean waters. We use "Rubby Dubby" (mashed fish remains) in tidal waters, to attract shark and the like. However, we have to use it in large quantities and often, as the tidal currents disperse it quickly. In the Mediterranean, such currents are much weaker, so ground baiting might last long enough to be effective.
Ground bait is easiest made with breadcrumbs. DRY the bread (rather than toast it) in a low oven. Then crush it into crumbs. It can then be mixed with fish oil, to give it flavour.
Presentation is easiest by use of a ground bait cage, attached to your weight (Plomb). This will disperse to provide a volume of flavour, along which the fish may be attracted, until they find your baited hook.
Other artificial attractants can make a difference. I find that a small piece of linen, impregnated with petroleum jelly and attached to the hook sometimes helps. Others use WD40 in a similar manner! There are, of course, a wide range of bait enhancers available on line, which can be used, either with breadcrumbs, or linen carriers.
There is also a range of plastic lures, the best known being "Berkeley Gulp", which may be used as static, or moving lures; also available on line.