"how do we help them to see us as useful to them?"
Very useful question.
It's hard to know how well 'outside groups' will fit/operate with the revised climate on lobbying. Not that PoP is about to have paid staff to do that sort of thing.
I think (hope) that there are now more people willing to do more than just turn up for a "demo" once a year - whether that's email politicians, join local organisations or start campaigns (or help with PoP!).
The way things seem at the moment (pre-election) is 'if you don't vote for us twice you don't really want the best for Scotland'.
I paraphrase heavily, and lump all SNP members/politicians/and some potential voters together there.
Assuming (as seems likely) the Greens get 7 or more seats, I think it would be wise for the SNP to offer Government roles (no idea if the Greens would accept). But there seems to be a remarkable degree of animosity, which presumably dates back to when the SNP needed the Greens for a majority - and then discovered it didn't.
Imagine Andy Wightman shaping policies on land reform or Alison Johnstone involved in Health or Transport.
If that's too 'radical', at least being in charge of more influential scrutiny committees.
If the SNP really wants Independence (which it does) it should be willing to see Greens as allies (after the election at least). In conventional left/right terms (which is not entirely appropriate) 'most' Green voters are probably more 'left wing' than 'most' SNP supporters. But they (and other parties too!) want "the best for Scotland".
Whether that's with Independence, more dual carriageways or fracking is (literally) debatable.
More of the same (in or out of EU/UK) doesn't seem like enough. Safer streets, more enjoyable/healthier ways of getting around hardly seem like dangerously radical ideas - and might well be highly cost effective - even using conventional economics.
Back to "how do we help them to see us as useful to them?" -
Well actually they are meant to be our "representatives", maybe they should think more about they could be useful to "us"!