You don't need the alum all the time.
If you do, rinse and apply the alum. Rinse it after 30 seconds with cold water.
Apply the lotion/balm after drying the face.
A balm is optional and only if you feel your skin tight. A good soap will prevent that. I found some connection between overshaving and skin tightness after the shave.
If post shave is very important to you, like me, invest in some great balms all around; Proraso Blue, Speick, Natura Siberica Yak & Yeti or The Sudsy Soapery Hemp Balm. You really don't need anything else.