a question about sacrifices and sacrifice showcase

It's like maths - you're trying to integrate without knowing what an area is!
You usually integrate to find the area.

And a really crazy Facebook game I posted recently on a forum topic here (I tried to add annotations on that post's PGN but it wouldn't work, twice in a row - guess I'll try again soon) - where I sacced a rook on the fourth (!) move but proved to be unsound. I would still like to hear from you guys what I should have played instead (my rating is so low because I've only played two games and I lost them both!
).
There were many opportunities to take pieces that you missed. When the rook captured on h2 you could have captured with your bishop. If the queen then came in you could have taken the queen with your king. Make sure you look at all the moves.

There were many opportunities to take pieces that you missed. When the rook captured on h2 you could have captured with your bishop. If the queen then came in you could have taken the queen with your king. Make sure you look at all the moves.
Thanks, but no, if I took the rook on h2 with my bishop, it would be Qxf2+ and mate in a few moves. Wouldn't be able to take the queen with my king because of the rook on f8.
Here are two of my games which involve some interesting sacrifices, good players can steer the game into where sound sacs are more likely, this comes with experience of playing many games, and solving thousands of tactical puzzles

tarikhk (1219) vs. radcamp45 (1335)
After 18... exd5, what's your followup? h6 will be responded with f6.

I generally don't make a sacrifice before calculating a good number of moves ahead in all variations and making sure that I will either mate, regain my material, or have very good positional compensation. As other people have said, if I have a large number of pieces near the enemy king or pointed towards the enemy king I will start checking if I have plausible sacrifices.

At the game: tarikhk (1219) vs. radcamp45 (1335)
at 20. i think you should have moved Ne5, then if he took ur Knight, u just go G7 and its over, but ofcourse he wouldnt have done that but, idk, maybe what he would have done is Qxh1+, then u just move Kd2, then whatever he did, u just try to block or threat or anything with your knight. Then u just go Qg7#
And if with his queen he took ur Pawn at Ph6, u just do Ph6 with the pawn next to it.

this is one game where someone sacrificed a rook against me to win!
http://www.chess.com/echess/game.html?id=14139975
Sacrifices are only sound if they can allow you to win the game! Generally most sacrifices win the game within a few moves while few last 8+ moves and allow the win. If you can see a win with the sacrifice within 4 or so moves its probably unsound. It take great brain power (and also most of the moves need to be forced) for more.

Here is a game I played where I sacrificed a rook and forced mate:
http://www.chess.com/forum/view/game-analysis/exploiting-weaknesses--pawn-mate
And here is another:
you could of also did ng5 and Qxh5! for blackburnes mate