Answer:-

Choose the safer solvent available for any given step of reaction. Minimize the total amount of solvents and auxilary substances used, as these make up a large percentage of the total waste created. 
Illustration : The main aim behind this principle is to use green solvents. For example, water, supercritical CO2 in place of volatile halogenated organic solvents, for example, CH2Cl2, CHCl3, CCl4 for chemical synthesis and other purposes. Solvents as chemicals that dissolve solutes and form solutions, facilitate many reactions. Water is a safe benign solvent while dichloromethane is hazardous. Use of toxic solvent affects millions of workers every year and has implications for consumers and the environment as well. Many solvents are used in high volumes and many are volatile organic compounds. Their use creates large amounts of waste, air pollution and other health impacts. Finding safer, more efficient  alternatives or removing solvents altogether is one of the best ways to improve a process or product.