If you are going mid then put ward on the enemy side of the ramp in the river so you can see and attack Bot all the time. Bots always know your visibility range and use it against you.

In the beginning if it's not possible to kill bots, harass them all the time. It's even better because they spend more time running to base and back and you outlevel them faster than if you kill them.

If you have a choice to last hit a creep or to deny yours then go for deny.