Hurry  spawn  in,  reinforce  the  walls.  Barricade the  doorway   and   try  as  hard  as  you  can  to make the area you are protecting indestructible.
  For this simulation, you shall be using a Brazilian operator called Caveira. Caveira has a very unique ability which lets you rush around the whole map unheard. Also, if she incapacitates you, she can find out your allies’ exact location. Now, enough of the chitchat; it is time to get to work.
There are three different game modes: Defend Area, Bomb, and Defend Hostage. First,I’ll explain bomb: there are two bombs and it is very complicated to watch both. The best strategy for this is to make a hole, so you can watch both at the same time.
All you have to do now is to wait for the attackers to come to you. The next mode we have to explain is called defend area. In this mode the objective is to keep the attackers out of the area you are protecting. So in other words do not let the attackers take one step in the area. A very smart idea to do in this game mode is to stay in the area you are protecting.
You are mainly just making the area that you are protecting impenetrable in this game mode.
The last game mode is Defend Hostage. This is the easiest game mode for defenders by far, because all you have to do is go in a room across from where the hostage is and wait for the attackers to come to you. The only problem with this strategy is that the attackers can sneak up on you. An easy way to prevent this is to check behind you every so often.
  I hope this has helped you at becoming better at defending in Rainbow 6 Siege.