If anyone out there thinks some kind of device will make them a good racer, forget it. Whatever class you choose to run will have everyone using the same rules. If you know what you're doing you should be able to have success in any class. A couple of good topics that could be started are How to cut consistent lights and How to tune and run the car to produce consistent ET's. Once you've got those figured out, driving the stripe gets a LOT easier.
The only thing I have to add here are the lessons I have learned racing my daughter in Jr. Dragsters the past 4 years. Racing Jrs is as pure foot brake bracket racing as it gets. She is a very consistent driver and cuts lights like I have never seen. In the past 4 years she has stacked up 8 .000 lights, as well as a slew of .00x and .0xx lights. The trick to being consistent is STAGING, STAGING and STAGING. You can not cut consistent lights NO MATTER WHAT without being consistent in the stage.
I know Jr racing is not Big Car racing, but it is the purest from of bracket racing. She can cut a light and drive the line. She has placed top 5 the past 4 years with culminating in the Championship this year at Numidia. We have won well over 30 events in total over 4 years and placed in the semis and quarter finals twice as many times. Whenever she is having issues on the tree it is always the stage. What has worked best for us is using a properly configured PortaTree to stay "warm" when not racing. You need to have it configured with the proper rollout which is very important if you want to cut good lights in the car.
Just my .02 from the past years coaching a very good and respected driver....
