With Vladimir getting lots of early farm is very important, you need to get your first item asap -Hextech Revolver- and you need to get to level 8 asap so your can Q can be fully leveled so you will have that extra health he gains from leveling. So during early game you don't want to be very aggressive, because if your to aggressive the champ your lanning against will kill you every time if they are good enough, to be very passive. Yes you can poke them with your Q but be careful and try to get as many last hits on the minions as possible. If you need some extra gold for an item or your having trouble getting very many last hits go over and get wolfs and wraiths (make sure to ask your jungler if it's ok first so he doesn't get mad). If your having trouble poking the other champ with your Q but (s)he keeps poking you and you need health you can last hit minions with your Q so you keep your health up and keep getting gold. One last tip early game if your having trouble keeping your health up use your Q as much as possible, it's about the same as drinking half a health potion.