As part of the small business I run (schedule C) I often give discounts, where would I report or claim discounts on services rendered?

As a cash basis tax payer, you need only to report what you actually receive.  You can just list your Gross Receipts or Sales net of any discounts.  In other words, just include the amount of funds you actually received.  An alternative would be to report gross sales that include discounts, and then report the discounts you gave as "Other Miscellaneous Expense" under "Other Common Business Expenses".