Wearing the right clothes on the job is important to success and advancement. The general rule is to dress according to the written or unwritten dress code of the engineering company. Many firms even include dress guidelines in job listings. The trick is figuring out the subtle stuff, especially if there is nothing in writing!
Ask the Director of Human Resources if there is a formal dress code. If so, read through it carefully.
Whether there is a written dress code or not, look around at other people working in the engineering firm. Most firms allow what is known as "business casual" clothing, though some will be dressed in suits (and ties for the men). Make notes of what you see, such as the kind of slacks women wear, types of blouses or knit tops, and whether men seem to favor collared golf-style shirts or cotton button-downs.
Sit in front of your closet and bureau with the dress code, or notes of what you have observed in the office. Organize clothing that will fit in with the style in the firm.
Make sure there are at least two formal business outfits in the closet for special meetings, especially with firm partners and client meetings out of the office. Take a cue from what the partners wear.
Check your hairstyle. Long hair on men is usually acceptable if it is well groomed. Women should avoid extreme styles or unusual hair colors (lose the hot pink streak)!
Double check before going to work. Make sure clothes are clean and pressed and look professional, even if they are casual. Ladies: leave the low-cut and tight stuff at home and make sure the heels are not too high. You should be able to stride down the hall or visit a job site. Guys: keep tie and suit combinations to the classics (striped tie and white shirt) if you are not sure. Of course, remember socks should match!