In addition to making good resolutions in the observance of mitzvot, and especially in mitzvot that have the special quality of providing protection, such as having one's tefillin and mezuzot checked, and praying together with the congregation and at the gravesites of righteous individuals, our Sages and the great leaders of Israel have recommended the following:
Reciting Tehillim (Psalms):
It is customary to recite the verses in Tehillim that correspond to the sick person's name, as well as the letters ק-ר-ע שט"ן ("tear up the Satan") found in the alphabetical acrostic of Chapter 119. Our Sages said: "Everything that King David said in the Book of Psalms was said on behalf of himself, on behalf of all Israel, and for all times." The Rebbe the Tzemach Tzedek explained: "The chapters of Tehillim shatter all bar-riers... prostrate themselves before the Master of all worlds, and accomplish their effect with kindness and mercy." The Rebbe encouraged that whenever Tehillim is recited, it is proper (on weekdays, of course) to give charity.
Changing a Name:
This is also one of the things that can tear up an unfavor-able decree. However, a name should not be changed except in exceptional circumstances and only after consultation with leading Torah authorities who are well versed in the inner teachings of the Torah. An expert Rabbinical judge (dayan) should also be consulted regarding how the new name should be used (for aliyot to the Torah, legal documents, and everyday life).
A Related Note: In recent years it has also become increasingly common to replace or amend a ketubah (Jewish marriage contract) when there are seri-ous marital difficulties or similar issues. However, this should never be done without the guidance of an expert dayan.
Adapted from Rav Yosef Ginzberg, Sichat HaShevua