How to dock if im on opposite sides of my target

[Grasss_eater]

I trying to dock with a satellite I made, but I've ended up on the complete opposite side of the satellite. What is the easiest way to get closer to the satellite without using too much fuel?

[Coyote Foxtrot]

You'll want to be on either high or lower orbital altitude to have a different orbital period so it can catch up to you or your catch up to it. After a couple of orbits it will be close enough that you can make a maneuver node to intercept its orbit with a close separation distance.

[jimmymcgoochie]

So you’re in the same/similar orbit as your target but on the wrong side of the planet? A phasing orbit is your best bet: set up a burn so that your apoapsis is higher and your orbital period longer than the target but with the orbits still crossing at some point, then add a second node after the first and move it forwards a few orbits until you find a close-ish approach. Tiny tweaks to the first node will shift the encounter so that you arrive at your target after a few orbits without using much fuel.

The greater the difference between your orbits, the greater the fuel use; conversely a very similar orbit will take a lot longer for one craft to catch up to the other.