Well when using smudge sticks the main part is sage. There are a variety of them. I am na sure if each variety has its own special mojo however sage in general is used to clear out any negativity.
Energy is like air. You can't see it, but like the wind you can feel it and like a smoker's area it can become polluted.
Nicotine can stain your clothing, hair, walls and more. You can see this residue.
Energy can't be seen ( well yeah it can if you have the knack for it) however it can be felt, and like a nasty stain it can leave mucky residue about.
The sage is lit and then fanned about. It is said to unmuck that stain and clean it up ( yay it like spirit bleach for your house!). You can smudge anything with sage.
If you want to follow up a regular ( no combination of sage n herbs) smudging with something else you can use:
Cedar to promote protection and attract prosperity and positive energy.
Or
Sweetgrass which also attracts positive energy, is light and pleasant feeling and adds a nice airy feel to the place.
These are three out of four Sacred Plants for the Native Americans. The fourth is Tobacco which was used as offerings to spirits ( I don't get the idea that you n Krispy will be using anything for offerings at the moment though however if you want to use tobacco as an offering you can put it in a dish and I would use some of that roll your own stuff....nothing like Newports or anything

).
If you want to try combinations of sage and another herb in your bundle figger out what would smell good together, look it up and see what its spiritual/metaphysical properties are.
For instance Lavendar is great for peace, calming and meditation ( aromatherapeutically it is a calmative).
If you wanted to add something for protection you could always get some Cinnamon oil or Dragonsblood oil and sprinkle that on your smudge stick ( do NOT handle the oil directly....USE GLOVES.....essential oils ARE EXTREMEMLY concentrated and are NOT good to touch or ingest....Tea Tree and Lavender are the only exceptions and even then there is a possibility of an allergic reaction).
At any rate I hope that helps to answer your questions.
Oh wait how do you use it?
Light it and waft the smoke around. It helps if you are in a cleaning and clearing frame of mind ( in a good mood, healthy, full of good thoughts on getting rid of ick). No point in cleaning the space around you if you are in a bad mood, sick or just put off now is it?
C/S/