Another bit of New GM Advice today. Often times it can be hard to make a plot that is convoluted enough to be interesting, yet straight forward enough to be easily followed. It can take a lot of work, and sometimes we just don't have the time to do that work. This has been the pitfall for many new GMs, making them unhappy with games that they run because they feel too simple. A quick way to fix that? Let the players do the heavy lifting.
Step 1: Do Some Random Stuff
The first part of your plan for this is to do some random stuff. Try to keep your stuff from being mutually exclusive with other stuff, but just get some stuff done. Perhaps on one day you want to run a bank heist, and then on the second day you want a murder to happen. So do them. Run the stuff you want to run, and don't worry about connecting the pieces. Just go with it, and when the players start to investigate put in some potential links, but things that don't necessarily have to play out. Do this for a few sessions, and then...
Step 2: Ask The Players What They Think Is Going On
This is where the players do your lifting for you. A few sessions in you ask what they think is going on, and they'll give you theories. Often times these theories will hinge on details you didn't even know you gave out. Some of the things the players will link will be linked in seemingly impossible ways. Seriously, I've had a player link a little girl missing her cat to a plot to assassinate the Emperor once, it was fun.
The best part here though is that some of these ideas and theories are going to sound good, or even awesome. They're going to sound like a very awesome and intricate plot. Grab onto those, remember them, and then...
Step 3: Make It Your Own
You can't just lift the idea as it is, you need to edit it a bit. Change a few things so that it isn't exactly like how the player said but is still close. Add a few twists and turns to it. However, your hard part is done.
While being somewhat lazy, there is a benefit to this. One of the things is that a group will come up with much more varied ideas than a single person. That is one thing you want to harness. The other is that you will be making your players feel smart, and involved, when things play out close to their predictions. Then, when you change things a bit, they still get the surprise and have to second guess things. It keeps things fun, gives gratification, and makes it easier for you.
Practice Makes Perfect
The first couple of times you try this method it may feel a bit slipshod. However, work with it and it can become a very quick way to help make things better. Hell, even in games where I have the plot done I'll often ask my players what they think is going on. Why? Well, for one it lets me see how well I am conveying the plot, and for two, they sometimes have much better ideas for what is going on then what actually is. Which means I can edit my plans to fit those newer, better ideas. Try it, and have fun with it.