I cannot stress this enough, especially the last part. I've seen a fair amount of individuals enlist and after a few years believe that they're a shoe-in for a slot even with lackluster performance and attitude. Work hard, have fun, but always remember you are being continuously evaluated. And remember Guard/Reserve units talk, so your history/performance will transfer down the line.
That being said, most individuals enlist, interview, and obtain a slot seamlessly with minimal issues. Good luck!