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When I focus with LiveView, I'll point the camera at a small bright object (e.g. Sirius or Jupiter), put it into Manual mode, set the slowest shutter speed I can (e.g. 1/30 sec), highest ISO possible (e.g. H1 - ISO expansion), and widest aperture that the lens has.
When I turn the focus ring, I can see the star become smaller, rounder, and whiter (i.e. no red or green fringing) the closer it is to perfect focus. Another option is to get the focus close, and then find the faintest visible star on the LiveView screen and adjust the focus ring so that the faint star is as bright as possible.
If I'm focusing with LiveView through the laptop, I'll zoom into 5x mode and set 200% display, and then use the operating system's accessibility tool to digitally zoom in even further so that the star almost fills the monitor. This lets me judge the focus from several metres away.
An even easier approach is to get software to make focus adjustments and check it for you automatically - e.g. Backyard EOS can give FWHM feedback in real time.
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