Sketchup, a program considered by some as a pain in the bum, and to others as a most amazing program. I fall in the latter category. If used correctly, Sketchup can do almost anything, from a simple chair to a detailed interior to an organic sculpture. (The latter will probably be extremely difficult to achieve without the aid of plugins however) I must stress the importance of keeping a Sketchup model clean, for modelling and sanity's sake.
Speed - We've all been there, where Sketchup begins to lag and this is most noticable when orbiting around. Here, we explore some techniques in keeping the file size down and also speeding up the modelling process.
Purging - a button that you should always be pressing. Purging essentially clears Sketchup of anything unused elements - components, materials, layers, etc. You should do this every once in a while to keep your file size down. You can either purge specific elements or purge the model as a whole. To do the former, let's take the example of purging materials. First, delete that Sang fella that shows up on Sketchup by default. Then go to the materials box and choose "in model". You will notice that there are all the materials that came with Sang. This is because Sang is not completely deleted. He is deleted from the scene, but not the model. To the right of the "In model" button, there is an arrow called "details". Click that and click "Purge Unused". Now, one material (white) disappears but the other colours remain. This is because Sang is still in the model. You can see this by going to components. You can purge him there, but I would purge the whole model. To do this, go to Window > Model Info > Statistics, then press "Purge Unused". This will purge the whole model of anything unused.
Edges - Turning off profiles and extensions will speed up your model immensely. By default, Sketchup turns these on. To turn these off, go to View > Edge Style and untick Profiles and Extension. These do nothing but make your model look bulkier and slow it down.
Textures and materials - It's nice to see a model with textures applied to it and sometimes it can be tempting to do it before you have finished modelling (guilty). Textures slow down models because Sketchup will need to recalculate the positions of the textures every time you move the model.
Low poly models - Every model is composed of polygons. The more polygons you have, the more Sketchup has to recalculate every time you move the model. When importing models from the Google Warehouse, try and find the lower poly models. Assess your scene before importing components. Take a classroom with lots of chairs for example - the chairs close to the camera would want higher poly models to reduce the faceted look. The further away the chairs are, the less polygons the chairs need as it will become more difficult to see the chairs.
Importing components - Quite often, when you import a model from the warehouse, you'll be flooded with new layers with strange names, dozens of materials that you don't need, and unnecessarily large file sizes. This happens when the uploaders of the files haven't purged or deleted unnecessary things in the scene before uploading. Before you import components, open up a new instance of Sketchup and import the component into there. There, you can purge or do whatever needs to be done before you copy it into your scene.
Shadows - Turn them off when working on your model. You only need shadows when you are rendering your final images and you need to check the position of the shadows.
Groups/components and layers - These really improve your workflow. Groups are usually used when there is a single instance of the thing that you want. Components are used when you have multiple items. Say you made a chair and converted it into a group, and you made multiple copies of it, when you alter one of those groups, only that one will change and the others will remain the same. On the contrary, when altering one component, all the components will change. So if you were working on a restaurant project where there were many identical tables and chairs, you would use components - if you ever needed to change a detail on the chair or table, you wouldn't need to go through each and every component, but just changing one will change all of them. Groups can be used in for example, when have multiple floors in a house - you can group everything in a floor as one. (By the way, you can have nested components/groups which means that you have a group within a group) The benefit of using groups/components is that you can hide these elements far more easily than selecting them individually to hide. This leads on to layers.
Layers are crucial to modelling in Sketchup, and naming layers is quite essential also. They help create a well organised file so that you can easily access different elements of your model. Take the example shown below (please excuse the poor naming of layers as this was a rather old model).
In this model, there is very dense and has quite a mass of 3D trees (very difficult to render!). As you could imagine, this model is very heavy in file size, and very difficult and frustrating to manoeuvre. All the trees are components and placed into a layer (TREES). (To place something into a layer, go to Window>Entity Info and with your selection highlighted, choose the layer you wish to place it into) When modelling, this layer would usually be turned off, allowing me to manoeuvre the model with much greater speed.
Hopefully that this tutorial is comprehensive enough for you to get a better understanding of Sketchup so that you can see the true potential of the software. I'm sure there are things that I have missed out here, but should I think of any more, I will edit this post.