Help with flying script

[HeyiDoStuf]

Hello everyone, im making a fly ability right now but i cannot for the life of me figure out how to make sideways flying.

can anyone help me? im kinda dumb

-- Config

local speed = 50

-- Variables

local cam = game:GetService("Workspace").CurrentCamera
local plr = game:GetService("Players").LocalPlayer
local uis = game:GetService("UserInputService")
local velocity = Instance.new("LinearVelocity")
velocity.Name = "FlyVelocity"
velocity.MaxForce = 9999
velocity.Enabled = true

local walkKeys = {Enum.KeyCode.W, Enum.KeyCode.A, Enum.KeyCode.S, Enum.KeyCode.D}

-- Logic

game:GetService("RunService").RenderStepped:Connect(function()
	local char = plr.Character
	if char then
		local humRoot = char:FindFirstChild("HumanoidRootPart")
		if humRoot then
			
			-- Rotator
			local rot2 = cam.CFrame.Rotation
			local rot = cam.CFrame.LookVector
			humRoot.CFrame = humRoot.CFrame:Lerp(CFrame.new(humRoot.Position, humRoot.Position + rot), .4)
			
			velocity.VectorVelocity = Vector3.zero
			
			-- Controller
			if uis:IsKeyDown(Enum.KeyCode.W) then
				velocity.VectorVelocity += Vector3.new(rot.X * speed, rot.Y * speed, rot.Z * speed)
			end
			if uis:IsKeyDown(Enum.KeyCode.S) then
				velocity.VectorVelocity += -Vector3.new(rot.X * speed, rot.Y * speed, rot.Z * speed)
			end
			if uis:IsKeyDown(Enum.KeyCode.Space) then
				velocity.VectorVelocity += Vector3.new(0, speed)
			end
			if uis:IsKeyDown(Enum.KeyCode.LeftControl) or uis:IsKeyDown(Enum.KeyCode.LeftShift) then
				velocity.VectorVelocity -= Vector3.new(0, speed)
			end
		end
	end
end)

plr.CharacterAdded:Connect(function(char)
	local childAdd;
	childAdd = char.ChildAdded:Connect(function(v)
		if v.Name == "HumanoidRootPart" then
			velocity.Parent = v
			velocity.Attachment0 = v:WaitForChild("RootAttachment")
			childAdd:Disconnect()
		end
	end)
end)

It is a localscript StarterPlayerScripts

[iBlyzer_A (iBellAether)]

Hi, your controller is not very efficient, what can I recommend, use, elseif, also, you can use lookVector (forward, backward), rightVector (Left, right)

[HeyiDoStuf]

i tried using elseif but i noticed you couldnt use multiple keys at once, also thank you!