Many years ago, I came up with a charting system of key signatures and their corresponding accidentals to assist musicians. It was a way to understand how to treat notes in certain keys. Take a look at the attached charts and see if you could benefit from them.
Remember: In the key of F, for example, unless a natural sign is given, the B would be played as a flat. In the key of D, there are two sharps, so unless otherwise indicated, F and C will be played as sharps. Flats of course are a half step lower than the original note and sharps are a half step higher than the original. Click on the below PDF attachments and enjoy!