The right preparation is more important in negotiation than having hard skin or a terror-inducing scowl. In an article for Inc., Robb Mandelbaum shares a variety of tactics that will get you what you want effectively.
The tips come in three phases, starting with before you get to the bargaining table. First, recognize your best alternative for if the deal falls through completely, so that you have a point of reference. After that, do as much research as you can on the person and/or group with whom you are dealing, to develop the most perspective on their needs and interests. Once the negotiation actually begins, Mandelbaum recommends going against the conventional wisdom of letting the other person go first and instead making an aggressive first offer. This will become an unconscious anchor in the conversation that could help to weigh the discussion in your favor moving forward. Another tactic is to make upward of three potential offers to the other side that are actually all of roughly equivalent value to you, even if the terms are different. In this way, you can learn what really matters to the other side and remix your offer accordingly.
Then when it comes to responding to their offer, make a counteroffer that is closer to what you truly wanted in the first place. Even if you like the offer they made, counter anyway, because if you accept right away it will make the other side feel like they made a mistake. If you must concede something yourself, try to take something else in the same stroke.
For even more tips, such as where to sit at a negotiation (Sit together at a table corner.) or the benefits of selecting where to meet, you can view the full article here: http://www.inc.com/magazine/20101101/how-to-negotiate-effectively.html