Once the fruit has set cut back the leaves to get sun on the bunches, make sure plenty of air gets through the vines to avoid mildew.
If you do start to see mould develop on the leaves give it a spray with sulphur solution (not in bright sunshine).
In the winter cut back everything to the old wood.
The grapes are not looking too healthy even the ones with sun and good air flow.
Most of the leaves and grapes here are from thinner vines above the thick vine
Most green growth is coming from these thinner vines in the middle of the main stem. The vine going off to the right from the bottom has no leaves or shoots coming off it.
Another grape vine on the other side has no growth apart from a small shoot at the bottom.
No idea this was being dwarfed by the other trees in the garden, will leave as is for this year in the winter will post up some pics and get some advice on what to cut off.
I won't even begin to advise, viticulture in Spain will be so different to here in South London and I won't post pictures of my twenty plus year old vine, you would laugh. Suffice to say it it is as neglected as the rest of the property you are going to have to do some serious remedial work, or just live with a crop that is way better than anything I can grow here. Hopefully some of the Greek or French (located) members will be able to offer advise.