You can't go wrong with flowers, incense, or special body oils. All these are used during Diwali.
Diwali, which is an especially joyous holiday, primarily focuses on worshipping Lakshmi, the goddess of wealth and prosperity. On the day before Diwali, Hindus shop for delicacies and fine clothes, and clean their houses and decorate them with flowers. On the evening of the first day, a single lamp is placed in front of the house as an offering to Yama, the god of death.
On the second day, Hindus rise earlier than usual, rub perfumed oil on their heads and bodies before bathing, then have a large breakfast with relatives and friends. Lunch is a feast with special sweet dishes, and oil lamps illuminate the house in the evening.
On the third day, all doors and windows are kept open so Lakshmi can enter the house and the front door, or the floor in front of it is often decorated with drawings or paintings of lotus flowers.
The next day, husbands give special gifts--usually gold ornaments--to their wives; since this is an especially auspicious day, the financial year now begins.
And on the fifth day--Sister's Day--men cannot eat any food cooked by their wives. Instead, a husband visits his sister, who applies perfumed oil on his head, arms, and back before he bathes, after which she moves a lamp in a circular motion in front of him to ward off evil. He then gives her a present, and they share a midday feast.
I'm Catholic. My mother-in-law, who is quite ill, is Jewish. Would she be insulted if I prayed to a saint on her behalf?
Pray away! We all pray to those beings or spirits or gods to whom we relate and in whom we believe. You're not asking your mother-in-law to pray to a saint. That surely would be inappropriate, just as it would be improper for her to ask you to go to daily services in a synagogue, put on tefillin and a tallit, and pray for her. Instead, you must approach the divine in the way you know how and deem effective, just as she'll do the same from her perspective.
But be cautious: If your mother-in-law does have a remarkable against-all-odds recovery, don't tell her that the saint to whom you prayed performed a miracle. She might think you're a kook. The age of miracles and wonders is supposedly over. She also might think you're proselytizing and overstepping your bounds as her daughter's husband. While she's ill, just tell her you're praying for her; if she beats the odds, just tell her that God must have responded to everyone's prayers. Saying "whose" God responded or which saint performed the miracle might be construed as a sign of religious bad manners and one-upmanship.
By the way, Judaism does have a very rough equivalent of saints. These "tzaddikim" model pious, righteous behavior. While at least 36 tzaddikim are alive, says the Talmud, the world cannot be destroyed. Biblical characters deemed to have been tzaddikim were Abraham, Noah, Joseph, and the prophet Samuel. Later, the kabbalists attributed divine powers such as clairvoyance to tzaddikim and said they interceded between God and the Jewish people. The Hasidim who came after the kabbalists used the term "tzaddik" for their leaders and said that God communicated through them to His people. Also said to have such supernatural powers as the ability to heal the sick, lay Hasidim would pray to their tzaddiks for good health or prosperity.
I recently visited several churches trying to find one right for me. Especially at the smaller Protestant churches, ministers stood at the church door to shake hands with parishioners and to welcome newcomers. At one church, the minister blocked the door, stopped me in front of the congregants, and asked for my mailing address. What should I do? Should I have escaped through a side door?
Such behavior is unpardonable. What's next? A body slam? A front tackle? A net that drops from the ceiling on all newcomers on their way out?
Many Christian services end with everyone turning to their neighbor and giving them the handshake of friendship. It'd be hard to be friends with a minister who's so determined to recruit a new congregant that he blocks the exit until visitors sign up on the dotted line. If this happens again, mutter something about mailing him your card--then promptly forget to do it as soon as you escape from the church. This is one church you don't want to come back to--and one minister who apparently sees his mission as church-building, not soul-building.