What is the most effective for garments merchandising and why? (Light, Colors, Space, Arrangements, Tidy Up and folding, music, smell or decoration.)

Light: clear white or yellow, so your garments can be seen

Colors: very clear or very dark, so it doesn't take away the attention of the garments you are selling

Space: as large as possible: people don't like to fight to be able to see it and no customer will have time to 'loose' if they have a first impression quick

Arrangements: depends on the style of your products

Music: has to fit the style of your garments and customers, don't choose the radio, advertising in the middle of a shopping day sounds very lame for any customer, but if you put a song you will have to check which once are free of law in your country before playing if you don't want a face to face with the authorities

Smell and decoration: depends on the garments of course (generally for smell: candles can be very a good deal as not expensive and last long).

I hope I could help but honestly with no more specifications concerning your garments, it is hard to give you a better answer.