Hi! To solve a potential flow past an aerofoil, which is suitable method-finite difference method,finite volume method or finite element method? Also what kind of grid should be generated?I am writing my own code

You should use a boundary element method (e.g. the panel method) since then you only require points on the boundary of the domain - because you are solving Laplace's equation the solution anywhere in the domain can be obtained solely from the boundary data.

Panel Method or boundary element method is more popular than other methods for solving Full Potential Equation.