I have a few tips. I love to suck cock, and have a minor gag reflex myself. But this has not prevented me from enjoying giving head and deepthroating many cocks.
I find one fo the best things to do besides swallow is remember to breath out your nose. If his penis is shoved all the way down your throat you might feel as if your choking. Take a second to breath through your nose and relax your throat. It helps to clam me down and gets rid of the chocking sensation.
And when your relaxing your throat really try and open it up. This oftens depends on the position your in and the shape of his cock. Sometime coming at it from above helps. Other times laying on the edge of the bed and letting him come in from above is best. That is actually my favorite position.
I have never met a guy I cannot deepthroat. I have rarely felt the need or desire to practice on an inanimate object. The only practice I have ever used was on a kielbasa/sausage a couple of times. The majority of my practice has come on real penises.
If you need any other adivce or tips on sucking dick please feel free to PM me and ask away.