I must admit that I found Round Robins also very confusing and far from easy at first (and second and probably a few more) sight(s). Now, I actually host one myself ( Postcard Set RR - The Sequel ) .
We always welcome new members and then I send them a mail in which I explain everything. I’ve received many positive reactions on this.
Mail sent to new members
Welcome in this group!
Now you’ve asked to join a group, you have accepted the rules that come with this Round Robin. Nothing different from all the other Round Robins though.
Once the group is ready to travel (and has minimum 3 members), it is my job to let all participants know the addresses and collections (if any). I usually do this every other Sunday evening when I have more time.
I don’t know whether you know how Round Robins work. You have to send each member one card of the RR’s topic. Check their collections (if there are any) to avoid duplicates In the big group (so not in a mail), you let me know when you’ve sent your cards. When you have received a card, you tag the person in the group and thank the person there. Make sure to mention the group number so I can keep everything organised too.
Unless you have successfully joined other RRs (one or more), I’m afraid you cannot join another group till your first cards have arrived. I hope you understand (it is a rule for all RRs on the forum). But you can rest assured that all participants report their cards as soon as possible. If you have joined other RRs before without any problems, could you please let me know which ones? This will allow you then to join more groups should you want to.
Do you have any collections or albums we can see? If so, could you please let me know the link? Is it all right then that I use this link for other participants to be able to send you new cards for your collection? I personally have all my collections on zonerama, this is a free website you can use to keep an order in your collections and where you can upload an unlimited number of images. Keeping and organising your collections in albums is quite easy and helps other members to make sure that you have a multitude of different cards. Of course, you don’t have to upload all your postcards, you could only go for the ones you really like or certain collections. Having an online album is certainly not a must, just a tip. After all, the written part of the card should make all the difference, even for duplicates. Another one that is often used is Flickr (up to 1000 postcards or photos, then you’ll need to pay). Both are very user-friendly.
Because sometimes the same members send each other cards for different groups, we have a special system here : Only if you see a 
or 
after the name are you allowed to send multiple cards in an envelope if this is more convenient for you. A means that your partner would like you to ‘fake’ a stamped postcards with used stamps and the address. In all other cases, your partner expects all cards written and stamped.
Could you let me know how you’d like to receive multiple cards from the same member?
as usual – all written and stamped individually- fake – sent in an envelope with other card(s) but looking as if were sent written and stamped
- in an envelope is fine (fully written)
I wish you many great postcrossing experiences here! Always willing to answer any questions you might still have.
I don’t really understand what you mean here. Don’t you just read what was written especially for you when a person tagged you? Of course, you can read all other replies too, but that’s not really necessary.
Exactly.
It is a fact that in the Postcard Set RR - The Sequel some groups need to wait a bit longer before they can start travelling, depending on interest. But other groups really travel on a regular basis. Any Postcard Box, for example, travels every fortnight with a minimum of 3 and a maximum of 5 people. It’s also fairly easy to see. If you’re the 3rd member, for example, then you know your group will start travelling the following Sunday (or the Sunday after that one, because I only send out groups every other Sunday).
You have given me a good idea though. I should mention the next ‘sending Sunday’-date (love the alliteration too 
) somewhere obvious so new (and old) members immediately see when the groups will start travelling. Thanks for that! 
It also solves your issue with ‘no deadlines’. Sometimes it’ll still be unclear, but from as soon as you’re the 3rd member, you know the deadline.
Now, to answer the initial question: I think it may be a good idea to inform new members about the possibilities of the forum more actively. Not straight away, but after a few weeks, as suggested by some.