What to pack for business trips?

Outfits

1. Dorothy Perkins paisley dress, Zara shoes, 

2. By Malene Birger linen dress, Paul Joe leather flat

3. Paul Smith Black striped dress, Tod's tods shoes

Accessories:

4. Longchamp folding tote bag

5. Alexander wang sunglass

6. Silk scarve

Deciding what to pack for trips is always so hard for me.  However I start by choosing a color palette and always bring a couple of cardigans and dresses.  When travelling ballet flats are my go to shoes.  I also always bring a shawl and bag that goes with everything in all types of weather.  But even with these rules it's still hard to pack!

What are your "MUST" items for travel?