IMO people are quite happy to see you have made an effort to look smart at an interview, even if once in the job you may be wearing overalls or something.
a dark suit, plain shirt and a plain tie are better than patterns or bright colours. If you haven't got a dark suit, grey trousers and light shirt rather than hoodie, cardigan, jumper, fleece etc.
Don't be substantially better dressed that the person interviewing you or he may not like it (£900 Italian suits etc)
Ladies should be smart not sexy if they want to be taken seriously (unless interviewing for pole dancer, club barmaid etc)