Step 1, Define the Battlefield. This is critical because you cannot prepare everywhere for everything. Determining the area in which you will fight will allow you to adequately determine later on resources required to effectively execute a course of action. Choose something too big for your organization and you will spread yourself too thin, choose something too small and you will be blindsided when the enemy comes at you from somewhere you didn't plan for. A good bet is to choose a small area for a specific operation then look at everything surrounding it within a reasonable distance (such as rocket fire range or range of enemy aircraft).
This can be a geographic area like a County, City, or neighborhood. It can also be used to define information ops, such as talk radio, internet blogs, cable news, local print media, international news organizations, etc. The more specific you make your limits the better your later planning will be. (Do you really think that the astro-turf campaigns of the Leftists don't hire people to call radio shows to discuss specific talking points?)
Important in this step is the terrain analysis of your entire Area of Operations. The acronym OAKOC will help you do this. For modern conflicts I recommend identifying Key Terrain first, and then identifying Key Terrain again after having looked at; observation and fields of fire; avenues of approach, key terrain, obstacles, cover and concealment. That will make you look at Key Terrain three times. In an urban environment streets and buildings are likely to be key terrain.
Drawing overlays on a map (for physical geography) or creating network diagrams (for cyberwarfare) or even spheres of information (for information wafare) will allow you to visualize the battlefield much better.
Step 2, Describe Battlefield Effects. This goes back to the "War Fighting Functions" to accurately describe yourself and the enemy. The more specific you can get the better. If the enemies Command and Control node is a specific server at a specific location that gives you more options than simply saying "the enemies main IP address is 192.168.1.1 or what not. If the enemy has a Movement and Maneuver advantage you need to know exactly where is their motorpool, what is the sustainment plan to support those assets. List out everything you have and the enemy has in terms of war fighting functions.
Step 3, Evaluate the Threat. At the start least this should be a list of assets and their capabilities, such as "the enemy has three platoons of four squads each. They are capable of engaging with direct fires out to 800 meters and can maneuver dismounted at 4 miles per hour over the terrain of our Area of Operations."
Once you have that complete, you need to pull the doctrine for how the enemy uses Platoons and Squads to create your doctrinal templates (how the enemy conducts operations without respect to terrain).
At the end of this you should know that in order for the enemy to be effective with his medium machine guns or heavy sniper rifles he needs to be no closer than X distance and no further than Y distance. Machine gunners need Fields of Fire and snipers need loopholes. The more accurately you now the capabilities and requirements of the threat the more likely you are to put them on your map where they will end up in real life in the next step.
Step 4, Determine Threat Courses of Action. So now that you know the enemies strengths and composition, this step determines the enemies disposition on the battlefield. The acronym AGADAP will help (analyze relative combat power, generate options, array forces, develop a scheme of maneuver, assign headquarters, prepare a Concept Sketch) to place the enemy on your map where they are most likely to be in real life.
Not listed is the enemy mission, and the more specific you can get about this the more it will help with arraying forces. If the enemies mission is to "secure the downtown financial district" it means he will array his forces there instead of the docks. Specificity is key to accuracy.
And that (temporarily) ends IPB
Now, once that is done you can set your recon elements out to CONFIRM or DENY your IPB and give you a clearer tactical picture before you start your plan on how to fight. Of course once you have new information it updates the IPB process as necessary. The more intelligence you can gather to confirm or deny the enemy composition, disposition, and strength, the more you are armed to respond in a manner that ensures success.