To memorize roots, you should remember the Arabic alphabet and differentiate between consonants that sound similar, such as "q" and 'k" and simple "s" and emphatic "s." Remember words with similar meanings and similar sounds. For example, mad-ra-sa (school), mu-dar-ris (teacher), dars (lesson). The common letters here are d-r-s They constitute a root with the general meaning relating to studies. Another example is: ka-tib (writer), mak-tab (desk), ki-tab (book). The common consonants here are k-t-b with the general meaning "writing."
Words constructed according to the same models sound similar, or at least they have the same vowels. You can recognize any model in a written version relying on consonants solely. That is why Arabs generally do not use vowel signs. For example, all adjectives sound similar, like ja-mil (beautiful), ja-did (new) and ka-bir (big). The adjectives referring to disabilities or colors use another unified model: akh-ra-su (dumb), at-ra-shu (deaf), akh-ma-ru (red), az-ra-qu (blue). The same principle relates to any part of speech in Arabic.
In addition to memorizing roots and models and mastering their combination, memorize typical phrases and sayings that can be useful in everyday communication--for example, ahlyan wa-sahlyan (welcome), salyam aleikum (greeting appropriate at any time of the day), ma khalik? (how do you do?), ana bi-kheir (I'm fine) and ma'a-s-salyama (goodbye). Repeat them aloud.
The most simple and pleasant technique of memorization is learning songs and lyrics by heart. Find transliterated versions of Arabic lyrics on the Internet and sing them together with a singer, paying attention to the pronunciation. Be aware that Arabs pronounce the same words differently in different Arabic countries. Some words in the so-called Arabic dialects (versions of Arabic in different Arabic countries) do not coincide with the Modern Standard Arabic words. For example, Egyptians pronounce "g" instead of "j" in "gomhoriya" instead of "jumhuriya" (republic).