One must first recognize that there are two kinds of shaving cream found in tubes and jars: brushless and lathering. No matter which you are going to use, it is most important to first prep your beard properly! Click here for how to prep.
Let us first talk about using brushless cream. As the name suggests these creams do not require a brush because they do not lather. To make it very simple, you squeeze a squib of the cream from the tube - or scoop a squib with one finger from the jar - into your hand. The size of the squib really depends upon the composition of the cream. If there are no instructions on the tube or jar, squeeze or scoop approximately an inch-long squib into your hand. Rub the squib onto your cheeks, neck, moustache, and chin taking care to rub the cream into your beard. Massaging the cream into your beard will both soften the whiskers and provide a better lubricated surface for your razor to glide over. That is all one need do for brushless shaving cream.
Now let us turn to using lathering cream. No matter which brand or fragrance of cream you choose there is a series of steps that you must accomplish prior to shaving with a lathering cream. The first step is readying your brush. While there are several approaches to this task, they all result in a brush that is more or less full of hot water. How hot is hot? Though boiling water is too hot for the badger hair, water in the range of 120°F - 150°F (≈49°C - 65°C) should not damage a quality badger brush. Taking care to not scald yourself or your brush, you may hold the brush under hot running water till it is well soaked. Preferably, place your brush in a mug or vessel containing hot water from the tap or heated in some other fashion allowing the hair to soak for three or four minutes. Alternatively, you may also use the bathroom basin partially filled with hot water to immerse the brush. You will see momentarily how the warmed mug or vessel has an excellent follow-on use. We are at the point where we need to transfer some shaving cream from the tube or jar.
If you chose a mug or vessel to soak your brush, you may wish to dump the hot water from the mug after removing the brush. Allow the brush to reduce its water loading until it stops draining of its own volition. No need to flick the brush. It will unload excess water without any help if you merely allow it to drip for a few moments. Now we need to transfer some shaving cream to the brush and produce our lather. There are numerous approaches to this task, each with its devotees professing their own way with religious fervor. We will discuss one and mention some of the others; thereby providing you with the opportunity to experiment.
Unless the tube or jar has instructions stating an amount of cream to use, squeeze or scoop a 1 to 1.5 inch (2.54 cm to 3.76 cm) squib of cream into the already warm mug or vessel. You will find that you can increase or decrease the amount of cream depending upon your results and the needs of your shaving routine. Some tubes have a larger orifice than others; some bathroom taps provide harder water than others. There are far too many variables affecting the amount of cream needed to have a one size fits all approach here. Your judgment and experience will eventually reign supreme. Now all you need do is whip the cream in the mug into lather and apply to your beard. The mug will tend to keep the cream and your brush warmer than if the brush merely remained at the side of your basin.
As for other lathering techniques, some gentlemen prefer to put the squib of cream directly onto the brush tips, others place it into their off hand, others put it to one side of their (emptied) washbasin, while yet others even smear the squib onto their cheeks much like a brushless. Specifically with shaving cream in jar, some prefer either dipping the brush head right into the cream (to lightly coat top hairs), or whipping the brush around the surface of the cream much as is done with a hard shaving soap in bowl. Arguing the relative merits or demerits of each of these approaches can start wars, but we are here to make lather not war. These approaches are provided for your edification and as a source for future exploration.
In the hustle and bustle of trying to get to work in the morning, shavers are apt to forget the importance of careful lathering in shaving. A barber’s razor made fifty years or more ago constantly reminded its owner on this point, for neatly etched on the side of the blade were the words “You lather well and I’ll shave well!".