Don't make it hard on yourself...

1) Takeoff

Most checklists tell you to trim to the neutral or takeoff position. This places your trim surface in a position for neutral pressure around Vy. As you lift off, you'll initially need back pressure on the yoke. As you accelerate the Vy, back pressure decreases, and will eventually be neutral.

2) Climb

After lift off, wait to re-trim the aircraft until you've adjusted your climb configuration. Retracting the flaps will cause your plane to pitch up or down, and you'll need to re-trim to keep the nose pitched for Vy.

3) Cruise

As soon as you level off at your cruise altitude, you start accelerating. Set your cruise power setting and wait for your airspeed to stabilize. While this is happening, start applying nose-down trim in small increments to prevent the aircraft from climbing. This requires some fine tuning, but once you're trimmed, you can let go of the yoke, and your plane won't pitch up or down.

4) Maneuvers

You should trim in every maneuver. Whether it's holding altitude setting up for a stall, or relieving control pressures in a steep turn, using trim during maneuvers will make you a master of the airplane.

5) Descent

This one depends on your descent. If you plan to a do a powered descent, you'll need nose-down trim in order to prevent the aircraft from wanting to climb again. If you do a power-off descent, you'll need nose-up trim in order to prevent the aircraft from pitching down too aggressively.

6) Traffic Pattern

You should use trim in each leg of the traffic pattern. Remember to re-trim the aircraft each time you reconfigure or change airspeed!

7) Landing

One place most people don't think to use trim is during the round out and flare. If you have electric trim, it makes landing much easier. As you enter the flare, add some nose-up trim to relieve back pressure. This helps you fine-tune your landing, and grease the plane on to the runway.