I find that very hard to believe about using the herb sweet grass. most spirits wants to be left alone. getting their attention is hard enough. unless you have a paticuler talent with them i doubt they would take any interest in you. they might but i wouldnt lay money on it.
You can look up the herbs for the different types of spirits you wish to raise; however, beware what you want and who you call. Permission is also needed to summon spirits. Do not play with this if you are not sure of what you are doing. The cabala of the Goetia will explain the consequences.
the spirit with me likes to be left alone, but i light incense for him, normally i use rose, or this type my occult shop sells called 'butterfly dream' in my opinion, i wouldn't try and attract a spirit, never know what could happen.