Sorry pal, I'm still stuck in League 2 with AFC Wimbledon in my 2nd season... The only tip I can give is to keep checking for free agents, as I have snapped up a few great signings on a free transfer including Emile Mpenza & Vincent Pericard (not bad for AFC Wimbledon in League 2). Also check the loan list often, as I managed to get James Tavernier from Newcastle & Martyn Waghorn from Leicester.
Tavernier could be a good loan for your League 1 Dover team, maybe check him out and make an offer!