The definition of Semi-formal

• Most people often confuse semi-formal with full dress. Full dress indicates tuxedos for men, which would be inappropriate at a semi-formal party. Top hats and fancy cuff links would also be overkill at a semi-formal party. However, you don't want to go too casual, so you'll want to avoid jeans, t-shirts, jerseys or sneakers. Think of what you might wear to church or a business meeting as a rule of thumb for semi-formal occasions.
  
  

The Best Shirts

• When attending a semi-formal, always go for the button up shirts with long sleeves. Color doesn't matter, as long as the colors in your tie match the color of your shirt. Cuff links can accompany your outfit as long as they are small and not too noticeable. Match your shirt with some nice black or blue slacks and a nice belt. It's your choice whether you want to wear a jacket or not
  
  

Jackets and Blazers

• The type of jacket you wear depends on the color scheme you are going for. As a general rule, jackets look better when the color of the jacket matches the color of the pants. If wearing a suit, wear a matching suit coat. If you're just wearing nice slacks, wear a color that matches or compliments the slacks. For instance, a blue or black jacket looks nice with tan slacks, but a blue jacket wouldn't look good with black pants.
  
  

Shoes

• Footwear is just as important as the rest of your outfit. The matching rule applies to shoes as well as jackets and slacks. Avoid wearing extremes, like white or other brightly colored shoes. Try to match your shoes to your belt. Wear black with black, brown with brown and so on. Go for dress shoes and avoid wearing sneakers, sandals or other casual shoes. However, your shoes don't have to be shined to perfection for a semi-formal party.