Just try keep enemies in your poison, and try to get rylai's first. In lane, build against your lane opponent, after getting tear. Getting first blooded is not an issue as singed, but still, DO NOT just give first blood. Once you are level 6, you have the option of running in between enemy turrets and killing the minions using your poison. You should be tanky enough to deal with the damage. If the enemy tries to gank you, run away, they won't bother chasing you unless they have enough cc to hold you still. If they do chase you, they will die. In teamfights, stand in the front to tank for your team and make the enemy walk through your poison. I am by no means a good singed player, its better you look up an actual guide.
I made this as a joke. (Not far from the truth though)