All humans enjoy getting licks from a dog on the face. This is a fact. Most humans pretend that they don't. (It's just a funny human quirk.) Therefore, you must be stealthy. The young are the easiest to access. Some are small enough that you can just walk up and lay your tongue on them. Others are bigger and you need to get onto your hind legs and lick them on the face. This takes some co-ordination but with practice you will get it. Kids absolutely love kisses. You do have to be careful not to knock the little people over. Occasionally, a little person looks like they might be overwhelmed and might cry. In this case it is good to have a human to re-frame the situation. "You got a kiss! You are so lucky!" This always gets them to smile.
Adults pose a problem because of their height. From time to time, you get an adult lower his or her face and say, "kisses," but it is rare. You really need to be an opportunist. For example, there is a 3 month old pup in the dog park, a lady bent down to give pats, I was nearby and lay a big kiss on her. It is important to always be on the look-out. Being on the couch with your people is a good time to get a kiss in. It is a good idea to make hay while the sun shines. If one of my people is lying down, I go in and get lots of kisses in before they have time to escape. I often find my other person will help out by holding down the one lying down so I can get more in. Of course, I am able to get non-face kisses in all the time.
Here is a photo of my big tongue. All the better to lick you with.
Life is great when you are giving kisses.