Ignoring him is good. But that means no telling him "no" and no touching him or putting your hands over his face. He just needs to learn that attention of ANY kind will go away when he jumps and bites. Without anger, without speaking or touching, abruptly get up and walk away. Do it consistently....and everyone who interacts with him must do the same. Reward him when he does not jump or bite. Let him know which behavior works to get him attention and a little treat and which behavior does not work. It will take absolute consistency from everyone. Be proactive by reinforcing the behavior you do like with something he absolutely goes ape over....a tiny, tiny piece of chicken or hot dog, beef, whatever....something really good. He'll learn which behavior gets him the good stuff.
Now, one thing that is important is teaching bite inhibition rather than no biting at all. That lunging and biting at your face is really no good at all so work as described to eliminate it completely. However, if you're sitting next to him say, on the couch and he mouths at your hand ever so gently, allow it. If it comes even close to pinching or hurting, yelp "ouchieeee," get up and walk away immediately. (every single time) He will learn to regulate his bite this way so that down the road if he does wind up biting someone, it won't be too hard. (not that a Chihuahua is likely to rip someone's face off like a big dog. LOL) Anyhow, it's a good thing for all dogs to learn. Later, you will teach him to only mouth gently upon invitation. For example, once he's learned that hard bites hurt human skin and will result in losing all kinds of good things; attention, affection, food, toys etc, but a soft mouth results in the continuation of these things, you can then put it on cue and get up and walk away for any mouthing that wasn't requested by you. (as an affectionate game) You want to be able to put your fingers in his mouth to examine teeth or brush teeth without being chomped on.
Associate examining his mouth and all over his body with good things. One quick look = a little treat/praise. Condition him to other people doing this too...the vet, friends etc. Grooming should be conditioned to be pleasant for him.
And remember...these lessons aren't learned over night. They're things that come with consistency and the dogs own maturing process. Just like little kids that do certain obnoxious behaviors....they learn over time, not suddenly.
