When you solve tactics problems, play it on the perspective of a defender and set up the problem on your chess board. Let say you have mate in 3 problem for white, take the black side. So you are looking for the mate threat in your black's king. You can also this with tactical problems like pin,fork,skewer etc.
Get Chess Tactics for Champion by Polgar. Aside from the typical pin,fork,discovery mate problems etc,this book contains game saving combination puzzles. It is a good book.
Take a look at these.
http://www.mark-weeks.com/aboutcom/aa03e17.htm
In my past couple of games, I have played terrible defensive chess.
How do you get better at defence? My calculation and visualisation isn't too great, but I struggle mostly with figuring out what moves to look at, like I'll get to a position in my head and ask "now what?" and won't find the attacking idea.
Are there any good defensive tactic puzzles? I'm looking for slightly more subtle, almost positionally inclined puzzles. I can't even remotely account for king safety in my evaluations simply because I don't quite understand the basics of defence.