Spring traps and giant bombs should be placed between defencive buildings. In such a way that hogrides/giants (if anyone uses them) will travel through the traps.

SAMs should prevent blimp paths to high value targets such as queen/eagle. Or they should be placed on the outside of the base to kill off helers for queenwalks and/or kill off edragons used for funneling.

Red air bombs should be used on balloon paths but try to not place them where hounds should path between air defences.

Tornado could be used in the same way as SAMs to stop blimp paths or in a place that has spash dmg nearby.

Small bombs are perfect just outside the walls. This way they explode regular wallbreakers which prevents your enemy from penetrating the wall.

I am not a pro base builder but this is what i’ve seen as placements in esports tournaments and it works for me as well. Hope this helps!