So what goes into this impression? It's a mixture of factors, some of which you can influence, and some you can't:
- physical appearance
- dress manner — are you friendly, relaxed and approachable?
- what you say
- how you behave
- neatness
- timekeeping
- attitude - enthusiastic, shy, etc
- personal hygiene and grooming
Most of these factors are subjective, not objective - that is, they cannot be measured, although some of them have at least some common standard. For example, although 'smart dress' is subjective, most people have a fairly clear idea of what they would agree is smart dress. Other factors such as physical appearance are very subjective indeed.
Given that, generally speaking, presentation is based on impressions that are subjective, just how can you prepare and make sure you present yourself well in all situations? You can't - not in all situations. You might turn yourself out spotlessly for interview to find that the company has a relaxed dress policy, for example, and everyone else is in jeans and shirts. What you can do is try your best to achieve a happy medium, so that you will do well in the majority of situations.