Omens and superstitions have been passed down from ancient times.
The correct interpertation of the signs from the gods used to be the province of arguars and soothsayers, but some of their knowledge became common property and has since passed into folklore.
Here are some good and bad omens.
And Cat Ailuromancy. Meaning of itches. Knifes and scissors . Spider  Arachnomancy.

Omens of good luck

Bats flying at twilight
A gift of a hive of bees.
A Robin flying into the home.
A white butterfly.
A four leaved clover
Hearing crickets singing.
Burning your fingernail cuttings.
Cutting your hair during a storm.
Finding a hairpin and hanging it on a hook.
Seeing a load of hay.
Looking up at the new moon over your right shoulder
Picking up a nail that was pointing towards you.
Picking up a pencil found in the street.
Keeping a piece of oyster shell in your pocket.
Carrying a rabbit's foot.
Walking in the rain.
Sleeping on unironed sheets (cool I never iron my sheets)
Spilling your drink while proposing a toast.
Breaking uncoloured glass other than a mirror.
Sleeping facing south.
A sprig of white heather.
A ladybird.
A bluebird.
A strange dog following you home.
Putting a dress on inside out.
Rubbing two horseshoes together.
A peapod containing nine peas.
A horseshoe.
Picking up a pin.
A wishbone.
Catching two rats in a trap. (not lucky for them though)
Sneezing three times before breakfast. (not lucky if you sneeze into your breakfast)

Omens of bad luck

Emptying ashes after dark.
A bat entering the home.
Putting a hat on a bed.
An owl hooting three times.
Wearing opal unless you were born in october.
Singing before breakfast.
Giving away a wedding present.
Borrowing, lending or burning a broom.
A five leaved clover.
Bringing eggs into the home after dark.
Cutting your nails on a friday.
Dropping a glove.
Bringing white lilac or hawthorn blossom into a house.
Looking at the new moon over your left shoulder.
Taking anything out of the home on New Years Day.
Peacock feathers.
Removing your wedding ring.
A rooster crowing at night.
Killing a seagull.
Mending somthing while still wearing it.
Putting shoes on a table or chair.
Dropping an umbrella.
Seeing  an owl in the daytime.
Putting an umbrella on a table.
Keeping slippers on a shelf above head height.
Blossom and fruit growing together on the same branch.
(except on orange trees).
Meeting a hare on the road.
Violets flowering out of season.
Meeting a pig immediantly after the weediong.(does the pig you just married count ?)
Meeting a grave digger. ( or a gold digger)
Buttoning a button in the wrong buttonhole.
Opening an umbrella indoors.
Putting on your left shoe before your right.
Sitting on a table without keeping a foot on the ground.
Killing a cricket.
A picture falling.
Breaking glass while proposing a toast.
Putting your shirt on inside out.
Getting out of bed left foot first.
A ring breaking on your finger.
Putting a pair of bellows on a table.
Three butterflies together.
Red and white flowers in the same arrangement.
Bringing christmas food in the home before December 24th.
Leaving christmas decorations up after the Twelth night.

Cats  Ailuromancy

A cat washing its face or ears, means rain.
A cat washing one ear three times. Expect visitors from the direction in which the cat is looking.
A cat following you means money coming to you
A cat climbing the furniture means rain is coming.
A cat that unaccountably leaves home means disaster
A grey cat is a sign of good luck.
A black cat entering the house is seen as lucky
A black cat crossing your path is lucky in Britian; unlucky in USA and some European countries.
A white cat crossing your path means illness coming.
A black cat walking under a ladder means bad luck for the next person to climb the ladder.
A cat sneezing on the day before a wedding is unlucky for the bride in the USA but lucky for a bride anywhere else.

Cat appearing around a  door . Think of a question and call for your cat.
If her right paw appears first around the door, the answer to your question is yes. If the left paw appears first the answer is no.

Meeting three black cats in succession is good luck.
A cat sleeping with her back to the fire means rain.

Meaning of itches

1 ~  Top of the head : Promotion , good luck.
2  ~  Left cheek or right ear : Compliments.
           3 ~  Right cheek or right  ear : Derogatory remarks.
4 ~ Left eye : Disapointment.
5 ~ Right eye : A meeting.
6 ~ Inside nose : Grief, bad luck.
7 ~ Outside the nose : Kissed by a fool, crossed, vexed.
8 ~ Mouth : Insults.
9 ~ Neck : Illness.
10 ~ Back: Dissapointment.
11 ~ Left shoulder : Unhappiness.
12 ~ Right shoulder : An inheritance.
13 ~ Left elbow : Bad news.
14 ~ Right elbow : Good news.
15 ~ Left palm or left ankle : Bills to pay.
16 ~ Right palm or righr ankle : Expect money.
17 ~ Abdomomen : An invitation.
18 ~ Loins : A reconciliation.
19 ~ Thighs : A move.
20 ~ Left knee : Gossip.
21 ~ Right knee : Good news.
22 ~ Shins : An unpleasent suprise.
23 ~ Left foot : An unprofitable journey.
24 ~ Right foot : A profitable journey

Knives and Scissors

Dropping a pair of scissors :
A disapointment,, which can be averted by stepping on the scissors before picking them up.

Dropping a knife on the floor:
A male visitor.

Scissors landing point down when dropped:

Crossed knifes:
Bad luck.

Breaking a pair of scissors:
Bad luck.

A knife left blade upward:

Giving a gift of  a knife or scissors:
This can cut the friendship unless a pin or a penny is given in exchange

A new knife used fisrt on anything other than paper or wood.
Bad luck.

Scissors hanging on a hook.
Good luck.

Spiders Arachnomancy

Seeing a spider in the morning ~ Grief.

Seeing a spider at noon ~ Anxiety.

Seeing a spider in the evening ~ Financial loss.

Seeing a spider spinning a web ~ some say this indicates that there will be a plot against you, others say it is a sign you will recieve a gift, probably new clothes.

Seeing a spider spinning in the morning ~ Good luck.

Seeing a spider spinning in the afternoon ~ A journey.

Finding a spider's web in a doorway ~  A visitor.

Seeing a spider climbing its thread ~ Good news.

Seeing a spider dropping on its thread ~ Good luck.

Finding a spider on your clothes ~ Money, a letter or both.

Finding a spider on your body~ Good fortune.

Finding a small red 'spider' ~ money.

Killing a spider ~ Bad luck.

Seeing a spider cross a wall ~ Good luck.