Q:

What is the most effective strategy to defeat a planet?

Inspired by these two questions here and here that contemplate similar issues, I’m now interested in finding the best strategy for defeating (not destroying) another planet.
The year is 2390. Humanity has taken to the stars and achieved interstellar travel. Humans now inhabit eleven planets in four different star systems. While most of these planets required sophisticated and expensive techniques to colonize (too frigid, barren, or hot to otherwise support human life naturally), two planets are beautiful terran-style worlds. One is Earth, and the other is (for the sake of this question) New Earth.
Sadly, diplomatic relations between these two planets have been souring for several decades and recently exploded into all-out war. Unfortunately for Earth, New Earth’s space fleets were much better prepared and have essentially annihilated Earth’s entire space-faring navy. At this point, Earth and its five billion inhabitants are now severely vulnerable, but can certainly continue to build threatening ships and anti-orbital defenses on the ground. As a result, they have not surrendered.
New Earth wants to ensure that Earth’s citizens are unable to pose a present or future threat to its new space empire while minimizing the cost to themselves. What is the best strategy to accomplish this?
Bonus Objectives
The most obvious solution to this problem is to simply start pushing (or dropping) moderately sized asteroids into the atmosphere. This is certainly a quick way to guarantee victory, but violates the following bonus objectives that the New Earth navy is hoping to fulfill with their strategy:

Earth-like planets are rare, so destroying the planet is not an option.
For the same reason, mass-extinction events that make the planet unsuitable for human habitation is not an option.
Massive loss of civilian life should be avoided if possible. It won’t look good on the news at home if millions of innocent people die.
New Earth wants an unconditional surrender from Earth.
Earth’s surrender should happen as quickly as possible to avoid public opinion souring at home.

Useful Information
This may be updated as more information is requested.

Wormhole-based FTL travel exists (hand waived) that allows medium-large ships to travel long distances quickly, but is expensive.
Earth is ruled by a single governing coalition.

A:

There are two main ways to do this that I can see, in addition to what has been suggested already.  

You turn things back to the dark ages by destroying modern shipping and infrastructure...or 
You take away the sun.

Option #1
As things now stand, any fleet that controls orbit can deny the planet the ability to reach orbit, because a rocket trying to escape gravity has no ability to dodge a missile or laser from space.  
The orbital fleet could also put a stop to all long range or slow moving vehicles...planes, trains, and most ships would be a thing of the past. 
This would set the planet's economy back many centuries.  If something isn't local, it can no longer be obtained, except by the extremely rich.  
The destruction of satellites would mean long range communications are crippled, especially if the endpoints of communication cables under the oceans are destroyed as well. This might be enough to fracture the world government into feuding regional ones, especially for areas that can't feed their people without food imports.  Those areas will be desperate to surrender once they begin to starve. 
But the space fleet could also target power plants, power transmission facilities, bridges, important factories, desalination plants, oil pipelines and refineries, mines, irrigation and water supply pipelines, communications and sewer infrastructure, all kinds of things.  
With orbital bombing, you could reduce a planet to the dark ages with tiny to medium civilian casualties, depending on how ruthless you wanted to be. Remember, a power plant has civilians in it, but you can just target the power transmission lines and facilities, and black out cities without killing a soul (but far more effort for the fleet).  
Similar rules apply for water, communications, and other resources.  It's too easy to hit things from space, and too hard to shoot back at the enemy, especially if Earth's military can't get any power or metal for the ground-based laser that they keep blowing up before it's finished anyway.
Option #2
To be even more oppressive yet impressive the fleet could deploy huge reflective sheets in an orbit identical to Earth's but close to the sun, so they cast huger shadows farther back from the light source.  If Earth doesn't surrender...You block out the sun with these reflective sheets.  
No light, no heat, no plants, everything dies without a bullet being fired.  Once Earth surrenders, probably within weeks, you simply rotate the sheets 90 degrees so they don't block any perceptible amount of light and things soon return to normal.

A:

Stuff a bunch of ships with small pieces of scrap, essentially giant pipe bombs, and detonate them in orbit. Assuming ground to space transport is similar to today's technology (chemical rockets) you've effectively blocked a spacecraft from safely achieving orbit, at very little cost. 
This has hopefully triggered what is known as Kessler Syndrome (https://en.m.wikipedia.org/wiki/Kessler_syndrome) as depicted in the film Gravity. As a bonus you probably take out the majority of orbital satellites dealing a blow to earth's communication network (furthering your other goals). 
If you're more interested in Earth surrendering, given the scenario of space dominance, you can simply set this scenario up without detonating the ships and hold Earth to ransom, merely threatening Earth to surrender or never be able to safely make it into orbit for generations. 

