Tasavvra-i-Asmi Allah Zat in English

the best and easiest method is getting the Ism e-Allah zat beautifully written by a Calligraper

and by observing its letters try to establish its impression onto one's heart and mind.

Then the Seeker should close his eyes visualizing said Ism and keep his inner self's attention fully focused on it.

If picture (Naqsh) of Isme-Allah is found difficult to inscribe (virtually) on every part of body then the place where it can easily be virtully written successfully and first concentrate on it with his Tawajuh and Reflection with eyes closed .

There is no limitation of time for practing Isme-Allah zaat, at whatever time you want you can do it. But the best time is from dawn of the day to the time when the sun has risen or the middle hour of the forenoon. When Isme-Allah zaat gets inscribed in the body of the Visualizer, it is seeen as written inside in lustrous letters (literals)and automatically takes its roots there at that point.