If you are researching in Kent, don't forget to look at the Online Parish Clerks site to see if your parish is listed.
The amount of information available online will vary but to see what can be done have a look at the Maidstone site which is treasure trove if you have ancestors from there.
Often there are directory entries, parish register transcriptions, old photos, maps, newspaper entries, probate transcriptions, sometimes a list of people researching in the area.
Definitely worth a look.
Other counties with an active Online Parish Clerk projects are :
Cornwall, Cumberland & Westmorland, Devon
, Dorset, Essex
, Hampshire, Lancashire
Somerset, now including Bristol
, Sussex ,Warwickshire and Wiltshire.