General Best Practices
When talking about what’s “right” or “wrong”, you should first understand that many of these rules are here to make sure that your equipment isn’t damaged- not really to make your equipment work better. Here are some good practices to maintain your microscope:
Focus with Course Knob First
If you’re trying to focus in on your slide, use your course knob only until you can see your specimen - then switch to the fine knob. This lets you save time because the coarse knob moves the stage of your microscope much more than your fine knob does. Switching to the fine knob allows precise movement and zooming while decreasing the chances of accidentally hitting your slide with your lens (which could scratch the lens).
Switch to your 4x lens
If you have a fresh new slide that you want to see, you’re going to want to start out with your 4x objective lens. Switching to your 4x has the benefit of first, it is much easier to focus than any of your other lenses second, it gives you a wide view of the specimen and lastly, it pretty much always prevents the slide from touching the lens.
Always Put on a Coverslip
Because there’s so much hassle trying to get the coverslip on and secured to your slide, it may be tempting to just skip this step of the process. In some cases, this could actually work out. But, most of the time, it’s probably better to get the coverslip on if you can. This firstly allows you to stop the specimen from touching your lens. It also stops your specimen from moving around when you move around the stage and helps you get in focus with your specimen.
Reset Your Microscope
When you're done with your slide, you should first “reset” your microscope before removing your slide. You can “reset” by just moving your stage all the way down and then switching your objective lens to 4x. This allows you to better set up your microscope the next time you want to use it and makes it easier to take out the slide from the stage.