Is it a good decision to work first and then do a masters in engineering ?

It is a very good decision to work before pursuing any kind of masters, let alone engineering. After working in the industry, you will have an inside track of how the industry operates on the ground level.Furthermore, you will also know which masters' course will advance your career best rather than simply choosing engineering as your post graduation major. In my opinion, every masters' student should have at least a year's experience.