First layer adhesion fixes 80% of FDM printing failures

If the first layer does not stick perfectly, the print will fail regardless of every other setting. Calibrate bed level until a 0.1mm feeler gauge drags slightly under the nozzle at all 4 corners and center. Clean the bed with IPA before every print. For PLA: bed temp 60°C, nozzle 200-210°C. For PETG: bed temp 80°C, nozzle 230-240°C. First layer speed at 50% of normal speed. First layer height at 0.28mm for a 0.4mm nozzle.