The Bardic 'grade' represent all the artistic and creative aspect of druidry; including learning the discipline required for creativity and getting in the right 'mind set' and state of awareness to find inspiration. My bardic skills, such as they are, are 'creative writing' but I definitely need more discipline and more inspiration....To live in the tradition of the ancient bards we might want to practice poetry and story telling, and perhaps we can enjoy the discipline of memorising, say, ancient sayings and story forms.
The Ovate - tricky one to 'modernise' as the ancient Ovates were seers and healers. I wouldn't recommend anyone who is an Ovate as a substitute for a doctor or nurse if you are significantly ill. To me the 'healing' that the modern Ovate can seek is 'self healing' principally - living a balanced lifestyle and finding psychological healing. What about the 'seer-ship'? Well I happen to think there are some interesting psychological lessons to be learnt from, say, using the tarot cards or other forms of 'divination' but I don't think they tell us a predetermined future. We find out something about ourselves, and the deeper we know ourselves the more we know our potential, our strengths and weaknesses, and thus to some extent mould our future 'in this sense'. I could therefore tentatively suggest that the modern Ovatic tasks are primarily 'Psychological'
The Ovate seer was also definitely interested in 'natural philosophy', what today we call 'science', but does not required that we become a professional scientist or even study for a GCSE in Chemistry. The ancient natural philosopher would study patterns in nature and draw conclusions. Ancient stone circles are for example testimony to their meticulous observational and mathematical skills.
To fulfill the Ovate grade I think we should just want to get to know something more, deeper and richer about nature, either the outerworld, the cosmos, or our 'inner world' (aka the 'Other World'). The typically druid interests include astronomy, meteology, and the ways of plants, wildlife, crystals (geology) but also the humanities of ancient history, ancient literature and the Celtic languages because a deeper knowledge of all these subjects provides great 'inspiration' as well as the process of learning and knowledge being a joy in itself.
The Druid grade is a combination of the other two grades and 'then some'. In particular the Druid (in the sense of those who have reached the Druid Grade) who has honed his creative skills and explored the depths of the outer and particularly inner worlds, will teach, organise rituals and perhaps have a leadership, administrative, or facilitating role in an organisation or group (without getting puffed up by any sense of grandeur or ego) and may instigate campaigns or activities either regularly or ad hoc. The ancient druids find their modern equivalents in priests (modern sense = celebrants?) teachers, lawyer-judges, mediators. By the time the Druid has reached the 'Druid Grade' (I don't use these terms interchangeably) he is going to have come to a state of being where he has found a 'Druid Philosophy' (conceptualised or not) that guides his or her judgements and decisions. So I suppose the characteristic of the Druid Grade is developing a 'Philosophy' (your own, not anyone elses!)
So for me at least, the 'watchwords' of the three traditional 'grades'are:
OVATE - PSYCHOLOGYDRUID - PHILOSOPHY
In my ever so umble personal opinion, I don't hold that a 21st Druid has to go through each 'grade' like some system of education or training to be able to call himself a 'Druid' in the sense of 'one who practises druidry'. There can of course be many advantages in a formal 'training scheme' and of course it is basic to OBOD druidry that one passes through the various grades. The main danger of such is that one does not develop original thinking and simply imbibes a particular system of belief that is not necessarily true to yourself.
I am sure that a coherent Druidry does involve elements of the bardic, the ovatic and druidic task discussed above which can individually or in combination be taken as far as our interest and resources wants to take them. Therefore one can be a great bard, a bit of an Ovate and occasionally do stuff like the Druid Grade. The last thing I'd want to import into my version of Druidry (having once thought otherwise!) is a rigid hierarchy with all the inevitable 'looking down on others' that can result.