Erev Shabbos –Halachos of Shabbos series with Halachos from HaShabbos BeTifarta by Rav Avrohom Adas, Shlita, of Yerushalayim:
a. The following points relate to the Melacha of Sirtut-or tracing lines in order to cut something properly (in the Mishkan, Sirtut was done on the Kerashim and the animal hides in order to cut them correctly):
(i) One should not fold over a paragraph or article from a Parsha Newsletter or the like on Shabbos in order to cut it out after Shabbos.
(ii) One may fold over a napkin into a basic triangular shape, even though he wants it to be an exact triangle, because the purpose of the line crease being made is not for cutting or writing--but for aesthetics. [One should be careful not to make special designs out of napkins because of the Issur of Boneh].
(iii) One may fold over the page of a Siddur or Sefer in order to remember something, because it is not being done for cutting or writing purposes. Similarly, one may fold a paper in order to put it into his pocket.
b. HaRav Aharon Kotler, Z’tl, would sometimes ride with a Lakewood cab driver who was not Shomer Shabbos. HaRav Kotler took of his valuable time to talk with him about the Torah and Kedushas HaShabbos during his rides. Once, during the Aseres Yemei Teshuva, HaRav Kotler told him--this Shabbos is Shabbos Shuva--this Shabbos you must keep and not ride! The driver became Shomer Shabbos.
Some dedication and effort on our part--and the Shabbos itself will do the rest!