Veigar Guide

Hi everyone, Anyone here who uses Veigar a lot? I bought this champ recently and tried playing with it, his skills are strong and I always build him full AP. The only problem I have is he is too squishy, I prefer using Teemo over Veigar but I think Veigar is a lot stronger compared to Teemo. You have any strategies on how to play well with Veigar?