I make sure the first posted... and then GRAB (copy/paste) the URL from my own wall. Send that in a message to yourself. Then, you'll have it at your fingertips (well, somewhat easy to get to by copying/pasting out of your message box). Put that URL in with anything you post every few hours, etc. along with "here's a reward for doing XXX, by the way, please help with my barn raising -> click here", etc.
I have ONCE (and only once) gotten the option from within the game (in storage item) to "ask for more help". So I keep the original "help me" link and republish it myself as needed. I hope this tip helps you!