When I design some hobbyist electronics, usually signals related stuff, if they have some noise, then I can take the FFT power spectrum, design filters to eliminate unwanted peaks. But this filtering path must goes beyond the hobbyists scope of view. I would like to know the your way related to your fields of experience such as audio, ECG, RF etc.
Also, I think, it is better to tell us, if there are any great books, tutorials, websites etc. related to noise filtering you know.
Thanks.