user7797: So I am a decent player, rated by my estimate at around 1000, even though my actual rating is 5 years and thousands of games out of date. In playing the chess engine in chess free on android, I quickly stopped playing 1. e4 because the center counter/scandinavian became very annoying. I switched to d4, and later to nf3 so that people playing against me wouldn't know how to react (most are sub 1000). I, however, don't know myself what the best response is. The two main lines are 1. Nf3 d5 and 1. Nf3 Nf6. I think that I prefer Nf6 for black, but how should I continue from there? Of course, it depends on what my opponent does, but what should be a position I aim for with black?

user2076: When White plays 1. Nf3, this is an invitation to Black to occupy the center. In most cases White hopes that he will be able to counter-attack on Black's central pawns.
Against this move, you have two choices:

accepting the challenge with Black: you play moves like 1... d5. If White is consistent with his plan, he could play 2. c4, to which you can (but are not forced to) answer with 2... d4 to grab some space and the fight begins



Or, completely different idea, considering that White is not taking the responsibility to claim for an advantage and that you don't want to do so either, you choose to play a quiet symmetrical line. The game could go on with 1. Nf3 Nf6 2. g3 g6 3. Bg2 Bg7 etc.

If you are interested to know a bit more about this opening, I encourage you to have a look to my introduction video to 1. Nf3: https://youtu.be/kfyB1W0ObyY

user4068: Try to answer 1. Nf3 with the King's Indian Defense setup.  This involves a move order such as 1... Nf6, 2... g6, 3... Bg7, 4... 0-0, 5... d6, etc., aiming for the pawn thrust e5.

user7500: Until you reach 14-1500 strength, opening theory is not very important. 
One of the best coaches in the world for beginners, National Master Dan Heisman, said:

It does not matter who gets the advantage out of the opening if one of
  the players is likely to lose a piece to a simple tactic in the
  middlegame. Losing a piece from an advantageous position will almost
  always result in a lost position. So study tactics, not openings,
  until you almost never lose pieces to simple tactical motifs.

However it is good to know the ideas behind opening moves, such as controlling the center, developing, etc.
So 1...Nf6 and 1...d5 are both good moves. They both control the d5 and e4 squares and aid development.

7797: <p>So I am a decent player, rated by my estimate at around 1000, even though my actual rating is 5 years and thousands of games out of date. In playing the chess engine in chess free on android, I quickly stopped playing 1. e4 because the center counter/scandinavian became very annoying. I switched to d4, and later to nf3 so that people playing against me wouldn't know how to react (most are sub 1000). I, however, don't know myself what the best response is. The two main lines are 1. Nf3 d5 and 1. Nf3 Nf6. I think that I prefer Nf6 for black, but how should I continue from there? Of course, it depends on what my opponent does, but what should be a position I aim for with black?</p>
 2076: <p>When White plays 1. Nf3, this is an invitation to Black to occupy the center. In most cases White hopes that he will be able to counter-attack on Black's central pawns.
Against this move, you have two choices:</p>

<ul>
<li>accepting the challenge with Black: you play moves like 1... d5. If White is consistent with his plan, he could play 2. c4, to which you can (but are not forced to) answer with 2... d4 to grab some space and the fight begins</li>
</ul>

<p><a href="https://i.stack.imgur.com/o3fjD.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/o3fjD.jpg" alt="enter image description here"></a></p>

<ul>
<li>Or, completely different idea, considering that White is not taking the responsibility to claim for an advantage and that you don't want to do so either, you choose to play a quiet symmetrical line. The game could go on with 1. Nf3 Nf6 2. g3 g6 3. Bg2 Bg7 etc.</li>
</ul>

<p>If you are interested to know a bit more about this opening, I encourage you to have a look to my introduction video to 1. Nf3: <a href="https://youtu.be/kfyB1W0ObyY" rel="nofollow noreferrer">https://youtu.be/kfyB1W0ObyY</a></p>
 4068: <p>Try to answer 1. Nf3 with the King's Indian Defense setup.  This involves a move order such as 1... Nf6, 2... g6, 3... Bg7, 4... 0-0, 5... d6, etc., aiming for the pawn thrust e5.</p>
 7500: <p>Until you reach 14-1500 strength, opening theory is not very important. 
One of the best coaches in the world for beginners, National Master Dan Heisman, said:</p>

<blockquote>
  <p>It does not matter who gets the advantage out of the opening if one of
  the players is likely to lose a piece to a simple tactic in the
  middlegame. Losing a piece from an advantageous position will almost
  always result in a lost position. <strong>So study tactics, not openings,
  until you almost never lose pieces to simple tactical motifs.</strong></p>
</blockquote>

<p>However it is good to know the <em>ideas</em> behind opening moves, such as controlling the center, developing, etc.</p>

<p>So 1...Nf6 and 1...d5 are both good moves. They both control the <code>d5</code> and <code>e4</code> squares and aid development.</p>
