How to create symmetrical and even struts

There are several steps to successful dockings. Click on images for larger view.

1. Set your target as your target.
2. Time your launch: A general rule of thumb is to launch when your target is just rising in the west (unless your target is in a retrograde orbit). If your target isn't in an equatorial orbit, then you'll also want to launch when the orbital plane crosses your launch site.
3. Launching: this is pretty standard. One key thing to remember is to set your apoapsis to meet your target altitude. Circularize as per the next step.
4. Closing the gap: if you're leading your target (in front of it), you'll want to increase your orbital period. Burn prograde to increase your apoapsis about 5km higher than your target, or until the intercept minimizes. In a similar vein, if you're trailing your target, you'll want to decrease your orbital period by lowering your periapsis. Also take this time to make your orbits co-planar by burning in the normal or anti normal direction at the descending or ascending node respectively. If you're already within about 5km, you can skip this step.
5. Initial approach: by now, the nav ball should be in target mode. In this mode, your velocity vectors indicate the relative velocity between you an your target. Keep your prograde vector pointed at the target, and reduce your relative velocity to under 50m/s. As you close in, continue making adjustments to your course to keep your velocity vector on the target indicator and continue reducing your relative velocity.
6. Final approach: by the time you're within about 1km, you should have a relative velocity less than 10m/s. Hopefully you remembered to orient your target ship such that one of the ports is pointing north or south (for equatorial orbits, normal or anti normal in general). Point yourself in the opposite direction, thus making the axis of the two docking ports parallel. Now you can switch to docking mode, as you don't want to use your main engine anymore. Change your view to Chase by hitting V a few times. Now use translation controls to line up the axis of your docking ports, thrust forward, and let the docking ports magnetism do the rest. Just not too fast. Keep it under 1m/s within 10m.

As a side note, I screwed up this particular approach because I wasn't paying attention and didn't reduce my speed as I closed in. I shot past the target ship and had to correct. Additionally, you'll note that I didn't in fact change to docking mode. This is a personal preference, and I use both hands on the keyboard to control my attitude with my left had (WASDQE) and translation with my right hand (IJKLHN).

• Do not decouple the boosters while also igniting the next stage. Put the decouplers and the next engine(s) in separate stages. Decouple the boosters and don't ignite the next stage until they drifted away to a safe distance. Even when the boosters have a notable spin, the relative velocity between core and boosters will be quite low, so a collision will likely be harmless. When you use a design with fuel crossfeeding where stages are separated while others haven't burnt out yet, put thrust to 0% while decoupling, and back to 100% afterwards. This makes the launch a bit less fuel-effective, but a lot safer.

• Place the decouplers as close as possible to the center of mass of the boosters to minimize rotation. The offset mode in the vehicle editor is very helpful for this, because it makes it very easy to adjust the mounting height of the boosters and the decouplers. Keep in mind that with a liquid fuel booster, the center of mass is usually further down because empty fuel tanks are quite light compared to the engine. But with solid fuel boosters, the center of mass stays in the middle.

• Replace your standard radial decouplers with the TT-70 Decouplers (those which are mounted on a girder assembly). The extra distance between booster and core might prevent a collision. To increase the distance further, you can place girder segments between decouplers and boosters. But then you will definitely need additional struts between booster and core to prevent the boosters from bending inwards during launch.