Do not practice on a banana. It can break. The toothbrush suggestion...I remember petite, who used to post on here a lot, mentioned it. You slowly desensitize the area...I will try and hunt down the links. Dildos...won't break, but also do not compress like a cock. Get a few, in varying sizes, and slowly start to practice on them.
Remember to not to inhale while it is back there. At a certain point you won't be able to, and, for me at least, that will trigger a gag reflex. Try to stick out and flatten your tongue, as this will give more space at the entrance to your throat.
Work WITH any curve he has, so if he curves down, kneel in front. Curves up? 69 time. Left or right? Approach from appropriate side. Dual curve ( my bf has a left ward) adjust to see what is easiest. Ramrod straight? Try to straighten out your throat ( laying on your back, head off the edge, or on your stomach, head tilted up)
If you gag...back off, get things calmed down, there is a Tom other than deep throating. When your ready, ease back down. There is a curve to your throat, do you will come to a point where you will feel some resistance. Moving your head side to side while pushing down will help wiggle past this sticking point. You may feel a bit of a...not a pop, but king. More like it will stick then woos your past. Lol
Swallowing helps. Big tome. It feels different and is harder to do, in my opinion, when you have a cock down there. Oh and don't try to be all worried about swallowing your spit. To get a good saliva swallow, I find it impossible with a dick down my gullet. If some drools out while you are nose in pubes deep, or when you get the hang of it and there is serious face fucking action going on, well, that is not the time to worry about some drool! They are not worried about anything other than how good it feels! Lol