Here are some tips to find users...
1st...place ad
2nd..look at people who need logos(they are supporters and you might get lucky and find a team without a PL)
3rd. go to YOUR FRIENDLY STAFF in the menu list...all staff members have supporter. I have 2 LA's and 2 GM's in my PL this time.
4. Go to the schedule page of the teams that have excepted your invite...now if thier PL has just finished(90% have just finished if they are looking to join a new one)..now click on the teams that were in thier last PL and see if they have found one yet. I once found 5 teams from the same PL that had just finished.
5. (the most time consuming)...Game time is huge to some members...so I went to all the Asian/ Aussie and New Z leagues(my PL was being played at 9pm on Friday JST) and clicked on teams who were supporter and found many team this way. I know for myself, I don't want to play in a PL that starts at 3am my time..
After 10 seasons of my PL(World Superleague) I am very fast at finding members.
BTW..6. Go to the PL ad thread and scroll back 3 months(the time it takes a 15 game league to finish) and check if a past poster has just finished or not..
Hope this helps