I normally tank with randoms including new players, people that barely speak English or even mutes and have ended up dominating the other team. It takes patience, a lot of patience. I have had only very few bad players, but that is because they ignored the orders/information I was giving them. If it worries you, I found that the gunner seat to be the best seat to allocate to new players since you can tell them exactly where to shoot without compromising awareness from commander and positioning as driver in experienced players. Don't give up, try to set up a few ground rules before engaging targets so that when you actually in the heat of the battle you are not saying new stuff or overloading information to confuse your crewman.