  Payment channel networks like Bitcoin's Lightning network are an auspicious
approach for realizing high transaction throughput and almost-instant
confirmations in blockchain networks. However, the ability to successfully make
payments in such networks relies on the willingness of participants to lock
collateral in the network. In Lightning, the key financial incentive is to lock
collateral are small fees for routing payments for other participants. While
users can choose these fees, currently, they mainly stick to the default fees.
By providing insights on beneficial choices for fees, we aim to incentivize
users to lock more collateral and improve the effectiveness of the network.
  In this paper, we consider a node $\mathbf{A}$ that given the network
topology and the channel details selects where to establish channels and how
much fee to charge such that its financial gain is maximized. We formalize the
optimization problem and show that it is NP-hard. We design a greedy algorithm
to approximate the optimal solution. In each step, our greedy algorithm selects
a node which maximizes the total reward concerning the number of shortest paths
passing through $\mathbf{A}$ and channel fees. Our simulation study leverages
real-world data set to quantify the impact of our gain optimization and
indicates that our strategy is at least a factor two better than other
strategies.
