Rendezvous

@QarabinaKa in KSP i always play everything manually without mechjeb.

sflanker's answer is excellent. There is a method that I use that doesn't require maths, although it is both fuel and time intensive. My method works as follows:
Set your craft up into a lower orbit than the target craft. Then set up a burn node that intersects the orbit of the target craft, and drag it along until the predicted rendezvous is as close as possible. I find that under 50km is generally alright. Burn that node, and then set your velocity type to 'Target' to get velocity relative to target. Wait until you are nearing the closest point, ideally a bit before, then burn retrograde on this until velocity is 0. Lock target, and burn towards the target a short while. When you look like you're going to swing past, burn Target Velocity Retrograde again, until velocity is 0. Repeat burning towards target and then burning retrograde until you are as close as you need to be. This method isn't as scientific or efficient as sflanker's, but it gets the job done for me. Hope this helps.

PCI stands for Planet Centered Inertial, which is a coordinate system that is centered at the center of mass of the planet whose sphere of influence you are in, and is otherwise fixed with respect to distant celestial bodies (i.e. the stars). It is basically the same as Earth Centered Inertial except for arbitrary planets including Droo.

Here is a diagram that should help explain

The green line represents the target satellite's position vector. The red line represents the launch vehicle's position vector. In order to find out the green and orange angles you have to know some things about your vehicles flight path: how long it takes, and how far it travels laterally. Once you know those things you can figure out what that red angle should be when you launch. If you do this you should wind up in orbit close to your target. The most reliable way to do all of this is to automate everything with Vizzy. Having an automated launch helps you have a consistent flight path, and doing this vector math and launch timing manually is a pain. However, if you don't want to use Vizzy as at least an aid for timing your launch you can always resort to doing the math on paper and slapping a protractor on your screen to time the launch.

@sflanker I’m assuming PCI stands for player craft inclination, and by angle between your crafts position vector and targets position vector Could you please elaborate if possible.

Assuming your target is in an orbit with zero inclination and you are launching from near the equator it is pretty simple. Estimate (or experimentally determine) the time it takes your rocket to get to your desired circular orbit, and the number of degrees of rotation in PCI terms that you travel during the launch. Wait until the angle between your craft's position vector and your target's position vector is equal to the number of degrees you travel during launch minus your target's angular velocity (degrees per second of rotation around the planet, aka 360 / orbit period) multiplied by the time it takes your launch vehicle to reach orbit. This angle will probably be negative, meaning that the target will need to be "behind" your launch vehicle at launch time, and you will have to account for that when waiting for the correct angle since the angle operator always returns a positive number, however depending on the launch vehicle this could theoretically be positive.

There are several examples out there of automating this procedure:

• Craft: Automated Rendezvous + Dock v1.1 by Gozinya
• Video + Craft: The Davinci Code
• Craft: Vizzy Program to Orbital Rendezvous by yours truly

If you are trying to rendezvous with an inclined or elliptical orbit, or you are launching from higher latitudes, then things are more complicated.