AP Blitzcrank isn't for playing safe, it's just a fun way to ruin fun for squishy enemies and get S+ for it. Don't use it if enemy team is actually tanky, and remember that this is a fun build, don't use it if you want to maximize Blitzcrank's potential in the support role.

Level 1:

Rush level 2

Level 2:

Q + E Enemy, if you don't think you can actually kill him with your adc, just use it as a poke, and run away. Continue till level 6

Level 6:

After you have gotten your first AP item, you are able to do your amazing combo:

Hook, Ignite, knockup, R, Run away with W and pray.

After laning phase:

Try doing ambushes on non tanky enemies for easy kills, side lane to push minion waves with your R, ward all important objectives, roam around the map near your teammates.

If your enemies on botlane are not willing to die, your best option is to find other enemies that will give you and your teammates some juicy gold by dying.