The codes and conventions of a thriller are usually easy to tell. you first have the technical techniques which are:

• Use of tracking
• Quick cuts 
•  Extreme close-ups/ close ups
• reveals (track in/zoom in)
• dramatic angles 
• eerie, tense music
• off screen sounds
• low key lightning
• strong directional lighting
• over exposed or color manipulation

You then have the narrative techniques which are:

• plot twists and turns 
• multiple lines of action 
• flashbacks
• red herrings
• chases/pursuits
• misdirection
• deadlines
• principle of concealment
• mysterious characters