I would not call it a lake. More like a river with some side branches. Fish the boat docks and you should do pretty good. I was out there Sat before our BBQ and went for a little boat ride. I would suggest working the docks up and down because there is not much else out there to fish. It is very populated.
Mcqueeny is crowded as Argo said. You would be better off going a very short distance down the road to Dunlap in New Braunfels. There is much more cover there and it is somewhat quieter. Fish the edges of the bunches of lily pads. My best out of there is just under 11 pounds. Soft plastics are hot right now.
McQueeney can be very good this time of year if you can stay away from the boat traffic. Get out early and fish the edges of the lilly pads and then move up the river and fish the boat docks after the crowd shows up. I had a day last year that we caught 15+ bass mostly in the 2lb range and 2 over 5lbs. I have also been skunked many times--guess thats why they call it fishing and not catching!!
PS--If you want excitement try using The Rat (floating plastic mouse/rat) in the pads-hookups are rare but well worth it.