How to be a better imposter:
Step 1: Don't kill or vent in front of people
Step 2: Make sure nobody knows where you've been, this is life and death.
Step 3: Make sure to sabotage every now and again to split up the crewmates.
Step 4: When you find your victim, and you are completely off-radar, kill them.
Step 5: Run to a safe place to hide or a nearby vent.
Step 6: Do not kill & report, this is most likely to get yourself killed, if nobody comes to report the body (let's say 20-30 seconds), then it might be safe to report.
Step 7: Don't be an ass and call out your imposter partner, that's just mean.
Step 8: When you are dead, you are still able to sabotage, closing doors and sabotaging is still and option, and do your partner a favor by helping him get his kills by closing doors or sabotaging.
Step 9: Also, when you are called out for some BS reason, don't say " ah you got me, 'name' is my partner, good luck!' " and then immediately leave. that's just for people who don't like to have fun.

Here's also a nice little mini-guide on how sabotages work!
Edit: I forgot to mention that sabotaging comms can also blind the task bar, this is very useful because when you're being watched faking a task, you can sabotage comms, wait 1 to 4 seconds, and then go.

• Sabotaging comms: (Skeld) Cameras and admin table are blinded
  
• Sabotaging comms: (Mira HQ) Door logs and admin table are blinded
  
• Sabotaging comms: (Polus) Cameras, admin table, and vital monitor are blinded
  
  
• Sabotaging Reactor/Oxygen: (Skeld) Oxygen is your best bet since there's a bigger split up in groups.
  
• Sabotaging Reactor/Oxygen: (Mira HQ) Oxygen is your best bet since there's a huge split up in groups.
  
• Sabotaging Reactor: (Polus) Splits up the group in a huge radius, including a vent for a sneaky kill (more info on that later)
  
  
• Sabotaging Lights: (Skeld, Mira HQ, Polus) Blinds fellow cremates, but keep in mind they can still see in a very small radius!
  
  
• Sabotaging Doors: (Skeld) provides a small window of alone-time with a potential victim, keep in mind the doors will automatically open after 5 seconds
  
• Sabotaging Doors: (Polus) provides potentially an infinite window of alone time with a potential victim, keep in mind the doors can easily be manually opened, but they will never automatically open.

Q = kill (Impostor)
Space = Open sabatoge panel (Impostor)
E = Use (All) / Vent (Impostor)
Tab = Open map (All)
R = Report corpse (All)

The Skeld Pros
• Large map with places to find kills in
  
• Good vent layout
  
• Good camera layout
  The Skeld Cons
  
• Too many proving tasks
  
• Vents aren't concealed in the fog of war
  
  7/10
  -----
  Mira HQ Pros
  
• Fun tasks
  
• Decontamination and reactor is a good place to hide in
  
• All vents are connected to eachother
  Mira HQ Cons:
  
• With a lot of long tasks, there will be a conga line in the medscan.
  
• No... Just... No...
  
• Small map with barely any kills to hide in
  
• Vents aren't concealed in the fog of war
  
• People can easily find out who the imposter is just by simply sticking together and calling out who wasn't accounted for
  
• You can see other player's usernames and blood splatters through walls at certain areas of the map (Such as through thin walls)
  
  4/10
  -----
  Polus Pros
  
• Big, open map to easily snag a kill in
  
• Fun & Unique tasks
  
• Good graphic design
  
• Original thoughts on the doors (Them remaining shut until manually opened)
  
• Good vent layout
  
• (In my opinion) A comedic and informative map trailer
  
• Unique sound effects
  
• Vents are concealed in the fog of war
  Polus Cons
  
• Lacking a 2nd critical task
  
• You can see other player's usernames and blood splatters through walls at certain areas of the map (Such as through thin walls)
  
  9/10