I won't tell you who to vote for but I would say you can check some websites on who conservative groups support.
Texans for fiscal respinsibility, Tea Party, DFW Conservatives.
Study some of these and you can get some good info.
I think Cornyn is counting on the NRA. In the last American Rifleman he had a thick two sided almost cardboard like ad. He seems to be buying a lot of ad time on conservative radio stations, which effectively stopped the hosts from saying anything bad about him. It seems he stands for big money, and is heavily politically motivated.
Lots of ads on KTRH (Houston 740am) but that hasn't stopped Michael Berry from talking bad about him and mocking the hell out of him 5 hours a day.
Gotta love all the fake ads for "John Wayne McCornyn" and how he's "just like you".