Wear a red bendel, a red string around your wrist, or a yad necklace, which depicts an open hand. These are thought to have kabbalistic, or mystical, powers to ward off evil spirits and encourage fertility. Jews from a range of observance levels may also wear these objects whenever an important life event happens, or simply in daily life for the benefits they are thought to bring.
Undertake a tzedakah, or charity project, to mark the occasion of your trying to conceive. This can signify that as you ask God to bless you with a child, you are also working to do good deeds in the world to honor God. In many Jewish communities, this type of activity is undertaken any time a significant life event is approaching, or any time a person is making an especially important request of God.
Visit the kevarim, or gravesites, of holy people and pray there for successful conception. The most sacred of these sites is Kever Rachel, the grave of the biblical matriarch Rachel, in Israel. The book of Genesis tells how Rachel said in desperation, "Give me children, otherwise I am dead." After a long period of infertility (during which Rachel is thought to have tried an herb called dudaim, which was thought to aid in conception), "God heeded her and opened her womb," and she gave birth to Joseph. Jews of all stripes may do this, but it is more common in observant communities.
Ask a kallah, or bride, to daven, or pray, under her wedding canopy for your fertility. This is usually done only in ultra-orthodox communities, although it is also seen in other types of communities.
Among Ashkenazi Jews (Jews who trace their ancestry to northern Europe), tradition holds that nothing should be purchased or prepared for the baby until he or she arrives, so as not to attract the attention of evil spirits.
One tradition of Sephardic Jews (Jews who trace their lineage to Spain and Portugal) is to celebrate a first pregnancy with a kortadura de fashadura, or "cutting of the swaddling clothes." Held during the fifth month of pregnancy, this custom involves a party featuring a ceremonial cutting of cloth to make the baby's first outfit. At the moment the cut is made (usually by a relative), the pregnant woman throws white sugared almonds onto the cloth--symbol of a sweet future for her unborn child. To find out more about this and other traditions, read "A Time to Be Born: Customs and Folklore of Jewish Birth" by Michele Klein.