You are tall and thin, you should choose a thicker one. The width is about 6- 10 cm.
Knitting is very good, because there are more colors, which can make up for the monotony of pure red dress color.
However, it is best to use light-colored belts, such as beige, light blue and orange ... be careful not to use purple and green ... it's ugly.
The pendant on the belt should not be too complicated, but delicate and firm. For example, some metal pendants similar to brooches will do.