What is best for spot cleaning?

Picked up my Alpine White 428. first day there where 2 tiny spots on the trunk, reddish and raised, I'm calling it road dirt. I rubbed them off with a little spit (yes, all I had handy) and used a micro fiber towel. Is there a product I can purchase and carry with me for these little clean ups for road dirt, bird droppings, etc.? Obviously I'm looking for something that will be effective but not hurt the finish.



Thanks in advance for any ideas.