The number one question that I get asked, hands-down, is "How do I use shaving soap?". And that answer depends on a few different factors. Lathering shaving soap depends on the soap itself, the brush you're using, and even the type of water. Everyone has their own technique so don't be afraid to experiment and find what works for you. I'm going to lay the foundation for you with a brief intro to the basics of lathering shave soap.
Identifying your soap and choose the best brush: You want to see if you've got a hard or soft soap here. Harder soaps tend to work better with stiffer brushes. I prefer a boar or horse hair brush for harder soaps. Some soaps won't dent easily with a fingernail, and some you can leave a thumbprint in. There are also many creams on the market, for those the Boar bristles will work just fine, but for a luxurious upgrade you can switch to a synthetic or silvertip badger brush. The softer bristles will hold more lather and make painting the lather onto your face a dream.
Loading Soap onto your brush: The next step is to get your brush loaded well with the soap. With boar brushes, you must soak them before use, but for synthetics and badger brushes, just wet your brush thoroughly and then shake it dry until it is damp but not dripping. Now swirl the damp brush to pack the bristles with soap. Your brush should be dry enough that you are not forming a lather yet, just caking soap into your brush.
Just add water: Here is where the magic happens! Whether you want to build lather in a bowl, directly on your face, or in the palm of your hand, slowly add water a few drops at a time until you get smooth, thick lather, look for micro bubbles and a silky shine. Lather should hold up and not dissipate over time.
Remember, every soap and cream is different: If at first you don't succeed, don't be afraid to adjust the ratios of soap to water. Hard water can also cause issues with making lather, may times more water is the answer, some people will soften their water with citric acid, or use bottled water to make lather.
Wet Shaving is an art form, and it takes time and patience and also your own personal style to become proficient. Good Luck!