Some customarily read shnayim mikra ve-eĥad targum on Friday and try to do the entire reading without stopping (Arizal; Shlah; Kaf Ha-ĥayim 285:3; Tur). Others follow the custom of reading one aliya each day of the week, so that on Shabbat they complete the entire parsha (Vilna Gaon; MB 285:8). In any case, anyone who completes shnayim mikra ve-eĥad targum at any point during the week has fulfilled the obligation.
Ideally one reads the Torah text twice, followed by targum. There are two customs as to how to do this. According to Arizal’s custom, one reads each verse twice and then its translation once. Following the custom of Shlah and the Vilna Gaon, one reads each parshiya (a section that in the Torah scroll is offset by spaces) twice and then its Aramaic translation. Both customs are acceptable (MB 285:2; Kaf Ha-ĥayim ad loc. 3).
Be-di’avad, the order is not critical. If one reads the verse, then targum, and then repeats the verse – he fulfills his obligation (Levush; AHS 285:3). Similarly if he reads the parsha out of order from end to beginning, he fulfills his obligation. The main objective is to read all the verses twice and the translation once. One teaching parsha to children need not read the verses twice and then the targum, because it is clear that while teaching he reads each verse twice and explains it (SA 285:6).
If one did not manage to complete shnayim mikra ve-eĥad targum before the Shabbat morning Torah reading, in principle he may do so during the Torah reading (SA 285:5). However, some say this is not proper. Therefore it is preferable that he read it quietly together with the Torah reader who is reading it aloud, and that he count this as one reading for the purpose of shnayim mikra (MB 285:14). If he heard the Torah reading but did not quietly read along with it, the Aĥaronim disagree whether this counts as one reading (ibid. 2).
One who learns the parsha with Rashi may, if it is easier for him, read an entire parshiya and then go back through it verse by verse with Rashi. However, he must read verses with no comments by Rashi an additional time, so that he reads them a total of three times. If he wishes, he can read the text twice with Rashi’s commentary, and then during the Torah reading he may read the parsha quietly together with the Torah reader, which will complete the third time for those verses upon which there are no comments by Rashi.
Women are exempt from the obligations of Torah reading and shnayim mikra ve-eĥad targum. Nevertheless, if they wish to participate in the Torah reading and study parsha, they are doing a mitzva (Peninei Halakha: Women’s Prayer 2:10).