Think of what the other person will perceive about you when they meet you.
As a simple rule of thumb, wear business attire – but you can vary that depending on the role you are being interviewed for. For example, if you are a highly creative candidate looking for a role in graphic design, you can probably express your personal creativity with your footwear and colour – but still ere on the business and professional side. If you are seeking a help desk position that requires you to move and repair hardware, you’ll probably choose more comfortable attire – not a formal business suit – but still ere on the professional side. You can relax more later once you know what the business climate is like in the firm to which you’ve applied.
In general, don’t wear sandals, no hats, no sleeveless shirts. For women, cover up – provocative clothing is less ideal in this context.