Determine what side the coin lands on. Execute the coin toss as normal by asking the other person to call heads or tails in the air, tossing the coin and catching it in your hand. Feel the coin with your thumb because the heads side has a smooth edge and the tails side has a rougher edge. Either flip the coin over or don't depending on how you want the coin toss to come out.
Spin the coin instead of flipping it. Ask the other person to call the coin toss before you toss the coin. When you toss it, instead of flipping it, flick your fingers so it spins but does not turn over. If you make the coin wobble a little, it will have the appearance of flipping.
Try to make the coin wobble without spinning it. Instead of spinning the coin, you can thrust it into the air with only the pressure of your index finger. If you do this gently, the coin will wobble but not flip over.
Use two trick coins to win a coin toss. Get one trick coin with two heads sides and one with two tails sides. Press the coins tightly together so one heads side is showing and one tails side is showing. Show the other person both sides of the coin quickly, but be careful so they don't get a good look at the sides of the coins. Before the toss, slip one of the coins into your pocket.