Set your line width to something under 0.5 points. At higher point settings RetinaEngrave will interpret the line as having two “sides”, and cut along each edge. (This can be a handy technique in certain cases.)
Specific settings for some packages:
Fills inside of objects can cause the laser to cut the shape twice – once along the stroke, and once along the outside edge of the filled area. This can cause scorching along your lovely cuts. To keep this from happening, remove all the fills from the version of your artwork you'll be sending to the laser.
Illustrator and Inkscape make different assumptions about the real-world size of an SVG “unit.” Illustrator assumes 72 units/inch, whereas Inkscape assumes 90 units/inch. This will cause the size of your artwork to change if you move between Illustrator and Inkscape.
To fix the problem, you can scale the artwork by these percentages:
Raster images for engraving are best set up at one of these resolutions:
Remember that raster engraving at 252 dpi is slow, and at 529.2 dpi it's twice as slow….
There is one higher resolution available on the laser, but it's not a very useful setting. At the highest resolution the dot size is actually smaller than the size of the laser spot. This will make images a lot darker than you expect. It's also really very very slow.