This is a hard one. With all the players on DDO, and the release (hopefully) of mod 9 coming in Sept (which may make it even harder to get good players in your party), I find the easiest way to get good player is to generally be nice. Newbies are the best source for this. You can mold them much more easily, especially if they are not guilded yet. By the time a toon is lvl around lvl 7, they should have a good idea as to what they are doing and may not need as much guidance. Basically, treat people as you'd like to be treated, with respect, and you'll have no problem gaining good players who will constantly be showing up in your parties, time and time again.
And if that doesn't work, try putting up a wet bar with caged dancing girls. When they sit at the bar to drink and watch, drop a cage on them and starve them into submission, that's how they got me.