Since i want to make this guide fairly short, i will only cover Impostor related stuff in this guide.
If you want to learn about the general gameplay, check out my Crewmate guide HERE.

• Try not to switch up your habbits; if for example you are playing Skiel and 90% of the time walk LEFT towards Top Engine, don't change where you go just because you are Impostor, that alone might certain kind of people suspicious.
  
  
• Start by fakeing multiple-step tasks such as Wires, but never do more than the actual Task requires.
  - Mind how long you do the task for, because good players will look out for that so know how long it takes to do tasks.

• Crewmate knowledge is really key to playing impostor because if you act like a crewmate you will be less likely to be suspected.
  
  
• One of the easiest way to get the first kill, is wait for somebody to be completely isolated, just you and them. If that's the case, then commit to the kill and try to diverse the Crewmates so that they don't discover the body, the best way is to simply sabotage on the other side of the map. (e.g. If you kill somebody in Navigation, sabotage Reactor.) This will help you get your kill cooldown without having to worry about people finding the body; and this can obviously lead to you going on a killing spree without anybody reporting bodies or calling emergency.
  
  
  After the first-blood
  
  
• After the first/second kill, it's up to you (and your Impostor friend) to play your cards right. Try to keep the Crewmates off of reporting the bodies as much as possible.
  - A good tip to do that is to try and kill people around corners and places where people don't intentionally go to.
  - Also, don't forget to kill the lights. Decreasing the vision of the Crewmates is great for hiding bodies and giving your kill-cooldown a chance to recharge.
  
  
• If somebody finds the body, try your best to clear yourself and maybe even accuse somebody out of the blue using a slip up that someone can make when explaining themselves.
  - Also, if you commit to a kill and see somebody running your way, you might aswell report the body and try blaming the whole thing on them using a variety of persuading methods.