Ask ten developers their recommendation you will get at least 8 to ten opinions.
My recommendation, using the following is to prepend a private variable with an underscore with the first letter lowercase. Static public and private methods camel case e.g. ReadProductsTask.
Don’t care for s_ prefix or t_.
In the end if this is for personal use, go with suites you best and when looking at a field for instance know by looking at the field know it’s scope. If working in a team or sharing say a GitHub repository there needs to be a unanimous agreement on how fields, properties, methods and delegates/events are named.