What can I say? I not only consider my advice to always be available via PM, but I have advised on private mail more times than I can count. I am always happy to do it, and I think, in a way, it is attendant in that situation to at least offer a polite acknowledgment even if you don't feel you can offer advice. But, as we know, a lot of times in this business, we can send out a request and never be met with a reply. All of the actors and creators I most respect, however, have shown themselves willing to advise me when I have needed their help, and I think it is good to pass this kind of attention along.
The only provisos are, of course, that sometimes a reply can take a little time - not everyone is immediately available to deal with unsolicited topics straight off the bat - but I always try and mail a quick reply to this effect if I know I won't be able to pay attention to a question for a few days! And that it should be recognised that sometimes no-one has the answers - and the best that can be given is some heartfelt advice.
Personally, I have tended to find that most of the regular forum posters (which is a small minority of CCP users, it's true!) are decent about response to private mails - it is fair, I think, to work on the assumption that most who have the time and inclination to share their advice on the forums are not averse to responding to enquiries in person. Whether you are likely to get a reply from more occasional posters etc. is a far more open question - they may not even be logged in to CCP with regularity. But, certainly, I work on the basis that the forum is itself a small community, and that, whatever the occasional disagreements that may emerge in the threads, we are all, at heart, already communicating already long before we start firing off private mails to each other...which, in itself, serves as an ice breaker.
It is always a good thing for older actors to help younger actors (although, as I think Mickey suggested at the top of the thread - how you define 'older' is an open thing). Most actors who are CCP regulars, I think it's fair to say, are ALL looking for breaks, young or old, but clearly some have amassed more years of experience in the industry than others...or in certain sectors of the industry specifically. In the days of rep, I think it was entirely common for the next generation to be coached, whether directly or indirectly, by the attitudes, experiences and qualities of the older generation whom they came to work with. Unfortunately (in my opinion), the current state of the industry is such that it is much more fragmented than the world of rep ever used to be, and one disadvantage of this is that it has lessened the regularity with which younger actors come to know older actors and vice versa. One of the nice things about the CCP forums is definitely that they go some small way towards rectifying that.