A few questions about long-term strategies

Re: sacing a piece for two pawns. Not good in most positions. Here you're up material before you do it, plus you get 4 connected passed pawns, so it's fine.

You should focus on activating all your pieces as quickly as possible. In the position before black's 16th, less than half of your pieces are working and you choose to move your f2 knight again. This is a common beginner-like error.
 

11.Bxf6 would be the idea that doesn't lose a piece to the fork you played on move 10, however white didn't play 11.Bxf6 so his 10th move is totally random. However even if that had been white's idea, it's no good because you had 10...Nxe4.

Bishop = 3 and knight = 3, so you're not letting anything go in exchange for anything. The situation was more like: white threatens to win your rook with a fork, so you defend c7 in the most natural way.

 

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Also the beginning was not standard at all.

3...d5? 4.exd5 Nxd5 5.Nxe5 wins a pawn for white

4.d3? is passive and allows 4...d4, gaining space with a tempo on the knight.

By the way, a "piece" in chess lingo means a non-pawn (and not the king).

So when I say "less than half your pieces are working" I mean you had 3 pieces on the back rank (two rooks and a bishop) and two pieces in the game (c6 knight and f2 knight).

Oh, and "..." after the move number means it was black's move. So 50.Nf4 would mean white's move 50 was knight to f4 and 50...Nf4 would mean black's move 50 was knight to f4.

To the first, the purpose of moving the knight twice at that point was to decimate whites king side and activate my last minor piece and I was hoping not to have to activate the queen side pawns to keep that end more defensive.

To the 2nd, thanks, I wasn't sure if I had it right. If he did follow up with that move I might have been in trouble.

To the 3rd, I generally value my bishops over my knights because I tend to force the open or semi-open games. Which is why I considered the beginning fairly standard. But I'll look into the line you said at the end of your post. Thanks 0110001101101000

In that position it was fine. In general though, even as a sort of golden rule for chess, you want each piece to be as active as possible. 

I understand you had different ideas for this game, but you asked about beginner strategy. The most basic for when you're ahead in material is to trade pieces. In the game you were up a piece, so what you aim for by making these trades is an endgame where they have only a king and pawns vs your king, pawns, and extra piece. This would be an easy win.

The fundamental way to force your opponent to trade is making your pieces as active as possible.

The subject of piece activity is getting off topic a bit, but I'll shorten it to say it's true for (almost) all positions that you want to move your knights, bishops and queen off the back rank as soon as you can, and your rooks to a central, open, or half open file.

There's an old quote to the effect of: beginners play by moving their best placed pieces, while masters play by moving their worst placed pieces.

Understood, thanks again. I recently started to learn backwards (endgame first, then mid, then opening) and that's part of the reason I used the knight sac. Hopefully, once I get better at the endgame I wont have to rely on that tactic. For now, more drills.

In response to post 4, one major mistake that you are making is valuing Bishops over Knights.

You claim you force the position open.  This is a bad idea.  Open the position when it's appropriate to be opened.  Don't just force the issue so you can view bishops better than knights.

Especially if you are Black, and you are behind in development, the last thing you want to do is open the position.

Opening the position should be done when you are ahead of your opponent in development, and you are ready to attack while he is not.

At the start of the game, I value my Bishops and Knights the same.  As the game progresses, they change in value.  You can't even say that "Bishops are better than Knights in such-and-such a position" or the other way around either!

Take a look at the position at the bottom of the message.  I put in zero effort to figure out the result with correct play - it's just there to make a point.

You have the following position with White having a Bishop on the board.  I didn't include the Bishop because it's unknown at the moment where it is.

If that Bishop is on say, d3, a light square, I could care less that the center is open and pawns are on both sides, the Knight is better!  Whether or not Black can win in this position is another question for another time, but White's bishop sucks!

Now let's say the Bishop was instead on e3!  By all means that Bishop is far superior to the Knight.  Black must constantly look out for sacrifices leading to an unstoppable pawn, and also White can play Be3-g1-h2 to get the Bishop into Black's camp.  All of Black's pawns are locked on the color square of the White Bishop, unlike the previous case where Black's pawns could never be touched, and White had nothing more than a tall pawn on d3.

So to go around having a preference of any form for one minor piece over the other is a major mistake.  I don't prefer Bishops.  I don't prefer Knights.  I prefer the minor piece best suited for the current position, and the example below even goes to show that "which bishop" it is also matters!  White's order of preference in that position is Dark-Squared Bishop, Knight, Light-Squared Bishop!

10. Bg5 dxe4 11. Bxe4 Nxe4 12. Re1 Nxg5 13. Nxg5 0-0 and you're just a piece up for nothing.

After 10.Bg5 dxe there's 11.Bxf6

So 10...Nxe4 should be preferred.