Ties are generally not necessary for business casual, but can be worn. Overdressing is not a bad thing and it never hurts to slightly overdress. You can always wear a tie and observe the other men at the gathering you attend to determine whether other men are wearing a tie. If no one else is wearing a tie, you can discreetly remove yours in another room.
Long-sleeved shirts are considered more appropriate than short-sleeved shirts, even during the summer months. The most appropriate shirts worn should be white, solid light blue, or conservative stripes. Tucked in Polo shirts are acceptable in more casual situations.
Wearing mid-calf length dark socks are appropriate so no skin is visible when you sit down.
Leather dress shoes should be worn. Sandals, athletic shoes or hiking boots are not appropriate in a business setting.
Facial hair should be well-groomed, if you choose to wear facial hair. Determine whether your company is a conservative environment and observe the other men in the company to consider whether or not your facial hair is appropriate.
If you choose to wear a watch, make sure it is conservative. Make sure any other jewelry you choose to wear is also conservative. Remove all earrings. Observe the other men of the company to see if they are wearing earring to determine whether wearing earrings is appropriate at the company in which you are working.