I was first dragged into using SketchUp by a co-worker who wanted to model our campus and put it into Google Earth. Having previously used a number of 3D CAD programs, I was more than happy to comply. As we worked on the buildings, however, my co-worker grew more and more frustrated with not being able to get SketchUp to do what he wanted it to. That was ten years ago and his frustrations stick in my mind today.
I think that the best place to start when using SketchUp, is to make sure that it is installed properly. On Windows systems, it is not enough to be the Administrator when installing it. On most newer systems, you should sign in with your preferred user account and then shift-right-click the package and select Run as administrator to insure that SketchUp can alter the permission scheme of the folders in order to function properly. The next thing would be to check the settings of the graphics card or internal chipset and make sure that it is configured according to Best Practices.
The next step would be to understand the user interface. While this seems like it should be self-explanatory, I would suggest starting with a simple layout. Hovering over one of the buttons will display the name of the tool and a brief explanation of its purpose (commonly called a Tool Tip). As the various buttons displayed below are understood and mastered (see the Reference Card in my last post for a more detailed summary), more can be added as desired. Start by keeping it simple.
One of the first How-Tos I read before first using SketchUp, was the suggestion to add the Large Tool Set shown above as well as the Views buttons. These are basically all that is needed to do the simple to the complex. Understanding and familiarizing oneself with them is the best place to start.
Once this is done, the next step would be learning how to navigate and orientate the workspace before moving on to anything more complicated. Start with a simple square or circle. Learn what Zoom Extents does. How do you Orbit the geometry? Or Zoom or Pan? What do those terms even mean? My co-worker had a lot of frustration with manipulating the geometry and its orientation to the rest of the model. Lack of understanding the differences of working in Perspective versus Parallel Projection views and how to orbit efficiently was a primary hangup.
Most new forum users will ask a simple question and be instructed to use Layers and Groups (or Components). My CAD background prior to SketchUp made this a no-brainer to me for anything more complicated than a shoebox. However, it was nearly two years into using SketchUp before I learned why you should keep (mostly) all of the geometry on Layer0. Also, you don't need to be creating an elaborate model to use groups to keep things straight. Once it's understood that Layers are not isolation boxes, but attributes of a group or component, keeping everything on Layer0 begins to make sense.
The manual has this to say about Groups and Components:
My rule-of-thumb for 35 years has been to treat every physical item I'm trying to model as a separate entity. While I can create a nut and bolt together, it makes more sense to put each in a separate group. And if I'm going to need more of them in my model, I make them into a component instead.
After struggling with orientation and views, my co-worker became frustrated trying to move things into place. A wall was easy to create, but it would stick to stuff when he tried putting it where it should be in the model. After putting things in groups, he was next frustrated in the copy-move-rotate class of modifications. Again, this was a basic lack of understanding about X, Y, and Z co-ordinate systems. The Red, Green, and Blue colors are there for a reason. It's a Good Idea to pay attention to them.
Which segues into the subject of Inferences. Inference, of course, comes from the word infer which means "deduce or conclude (information) from evidence and reasoning rather than from explicit statements." In SketchUp, this means having the software try to understand what you want to do and provide helpful hints as needed. Understanding the various types of inference is critical to learning how to use SketchUp and it is the key to creating the geometry you want correctly.
The manual says this about Inference:
From this point on, I think that it should be smooth sailing for even novice captains. And, if they happen to need some help in navigating the shoals of SketchUp, they will be better able to frame their questions and understand the solutions and advice they are given.