bit-tech published a guide to Engraving your case
I can only say that there are thousands of small tricks and techniques that you can use to perfect your design, but I've tried to get in all the basic things that you need to think about in this guide. Engraving is great fun and it can take your mods to a whole new level. Its easy to get started and if you only take it slow and don't rush your work, you will get good results.Engraving 101