• Keep the bed clean, any dust, oil and grease can accumulate over time and will cause print to not stick on the bed. 
    • To clean the bed, you can use Isopropyl/methylated alcohol or acetone  with a paper towel/micro fiber cloth.
    • you can wash under warm soppy water and dry and clean off with isopropyl/methylated or alcohol.
  • Printing PLA set the bed to 60-65°C , if you have warping in corners you could consider glue stick or bed adhesive like Magigoo or enable brims or ear/corner brim in the slicers.
  • Printing PETG on Glass (80-90°C) is possible but will require a layer such as glue stick, hairspray, Magigoo, Dimafix bed adhesive. 
  • Reduce first layer printing speed(10-20mm/s) and for smaller object brim may be required or for larger print ear/corner brim is recommended.
  • Wait for the bed to cool before removing the print.