Kindly reference the following link(s):

Sorcerers, Amulets and Talismans

Going to 'Peers' to solve problems - is it Shirk?

Going to Peers and Maulanas & Ruling on hanging Ayahs of the Quran on walls

Fortune telling and Claiming to know the Unseen 

Can Sheikhs or Peers control or catch Jinn

Ruling on Numerology and Horoscopes | Sheikh Assim Al Hakeem

Bad Omens about house etc | Sheikh Assim Al Hakeem

Is it possible to know who has done black magic on you?

Believing in good omen is something positive as a person believes that it is a sign from Allah and that all that is good comes from Him. Believing in bad omen is Shirk as it is negative thinking and it is believing that something bad is to happen due to an accident or a bad name called in front of you.