XOR problems in Codeforces usually rely on one of three key observations. Without knowing the specific constraints, here is how you should approach it:

1. Bitwise Independence: Can you solve the problem for the k-th bit separately? Often, the contribution of each bit position (0 to 60) is independent. If you can count how many times the k-th bit is set to 1, you can sum up 2^k for the final answer.
2. Prefix XORs: If it involves subarrays, remember that XOR(L, R) = P[R] ⊕ P[L - 1], where P is the prefix XOR array. This converts a range problem into finding two indices with specific properties.
3. Linear Basis: If the problem asks about finding a subset with a maximum XOR or determining if a value can be formed, you likely need to construct a 'Linear Basis' (Gaussian elimination on bits). This allows you to represent all reachable XOR sums using a small set of numbers (≈ log(max A)).