How should I go on about putting sanity checks on gun?

Someone reccomended me in the dev forum that I check if it hit something in the client so I made the ray in the client

and this is my local script

local Remote = game.ReplicatedStorage.RemoteEvent

local Tool = script.Parent
local Handle = Tool.Handle

local Player = game:GetService("Players").LocalPlayer
Tool.Equipped:Connect(function(Mouse)

    Mouse.Button1Down:Connect(function()
        local ray = Ray.new(Handle.CFrame.Position,(Mouse.Hit.Position - Handle.CFrame.Position).Unit*800)
        local part, position = workspace:FindPartOnRay(ray, Player.Character, false, true)
        local Humanoid = part.Parent:FindFirstChild("Humanoid")

        if Humanoid then --If Humanoid is found

Remote:FireServer()

        end
    end)

end)

But What I dont understand is how would I damage the person safely so that no hacker can just fire a remote to exploit

my server script

game.ReplicatedStorage.RemoteEvent.OnServerEvent:Connect(function(player)

What checks should be put here?

end)