Here are some notes to consider in using this guide prior to reviewing the strategies involved.
This uses version 1.7
The goal of each mission is to develop an early economy, an adequate defense, and a strong attack force to use in calculated attacks.
Efficiency/speed is of prime importance in many missions because you are racing the enemy to acquire more spice, therefore more resources, and therefore greater opportunities to achieve victory.
One other note on efficiency is I always use concrete slabs for my buildings no matter what. The purpose is to increase efficiency and save money. Repairing a Windtrap from 50 power to 100 costs more than 20 credits(cost of slabs). Likewise a fully repaired refinery will bring in spice faster than if it is half-destroyed. Most buildings function much faster at full health as opposed to half health. So, try to keep buildings repaired except later in the game when the urgency of speed is not as important. It is also likewise better to upgrade buildings as soon as you can so you do not pay the cost of repairs if you plan on letting them go to waste. This depends on you and what you are willing to pay. Just note that I value slabs and while it may be possible to win without slabs, I prefer not to give that chance. One other note of which I am not sure of its validity, but it seems that when you don't use slabs, buildings fall into decay faster than they otherwise would.
In my opinion there each house presents an overall level of difficulty. Harkonnen=Easy, Atreides=Medium, and Ordos=Hard. The reasons for this is the availability of weapons to use in offensives, as well as the weapons to face. Without giving spoilers, we'll just leave it at that.