If you wish to undertake maintenance to your Suzuki Boulevard M90 then it is always a good idea to have access to a Workshop Manual to use as personal reference in case you need to know ways to take out a certain component for example, the Brake Pads and fit it again efficiently.
Suzuki Boulevard M90 Workshop Manuals will give specified diagnostic guides for your car therefore if something is wrong it can help you figure out what the issue is and some ways to repair it. You can then determine if this can be done by yourself or in case the job is just too big you can actually make a reservation for your Boulevard M90 into a trusted repair garage.
Suzuki Boulevard M90 manual