Pesticides n whatnot

Can anyone tell me if I can or need to add something to my soil to keep bugs n whatnot away or jus do my best to keep temps right. N if something happens take care of it then or is there a way to prevent it or maybe try too… I have no bug or mildew mold w.e but I jus wanna get my protection together n Kno do I need it now or when it happens

Neem oil, and spinosad are the two I keep on hand. Captain Jacks dead bug is a name brand of spinosad.
For the most part, either of those will kill bugs, and neem oil can be found in an organic version.