For a Service Management:
For a paid services scenario, the sequence of transactions are like this:-
IW51: create notification: use a Revenue bearing notification type
IW34: create service order with revenue bearing order type
IW41: Confirm your service order operations and do goods movement if any.
DP90: create Resource Related Billing Order
VF01: create RRB invoice against the RRB order
The above invoice will be debited to the Customer account. While the Cost of Services rendered account will be credited.