Battery energy storage systems (BESSs) are more and more considered as a potential asset to provide frequency containment reserve (FCR) services. In practical deployment, it is challenging for the BESS owner to secure benefits when submitting bids for FCR one day ahead under the uncertainty of prices and frequency deviations. Moreover, the energy capacity constraints for such a system make it difficult to assure the availability of the reserve over the day without knowing in advance the need for regulation. Thus, in this paper, an operational planning consisting of a look-ahead bidding strategy followed by a rule-based control is presented for a BESS participating in the FCR market. Historical data are used to compute the day-ahead bids before four different controllers are proposed for real-time operation on the day of delivery. Yearly simulations show the trade-off between profits, penalties for non-activation, and BESS lifetime. The results show that corrective charging/discharging in real-time enables the BESS to achieve up to 97% of the maximum theoretical profits.