Learn the numerals 1 through 10. Learn how to write them and say them. The numerals used in English are actually borrowed from Arabic, called Hindu-Arabic numerals, and are already used in most Arabic-speaking countries. There is an additional set of characters that represent the numerals in Arabic as well, so learn those.
Memorize from 1 to 10: wahid (1), ithinin (2), thalatha (3), arba'a (4), khamsa (5), sita (6), saba'a (7), thamania (8), tisa'a (9), 'ashara (10), and zero is sifer.
Memorize from 11 to 20: 11 and 12 are singular words "hidashar" and "itnashar," while the rest of them are the unit number plus a "t" sound, and "ashar" for 10. For example, 13 is "talatashar," 14 is "arbatashar," and so it goes through to 19. In Arabic, 20 is "ishrin."
Learn the system for making numerals higher than 20. This is very similar to the old English way of saying a number: "one and twenty" for 21, in Arabic is "wahid wa (and) ishrin."
Learn 30 through 90. The basic rule for these numbers is to take the unit number and add an "in" sound to the end. For example, 30 is "thalatin," 40 is "arba'ain." Then you get to 90, "tisain," and 99, which is "tisa'a' wa tisain."
Learn the larger numerical groupings. 100 is "mia'a," 1,000 is "alf," and one million is "millio'an."