What will be a good LH count after 10 minutes

Pretty new to Dota 2, I've practice with some hero and I seems to have a hard time last hitting when I have a melee hero. I seem to be a bit afraid of going through the minion and getting harassed by the enemy.

When I play mid, I'm mostly with a ranged hero, so I don't have any problem. So I need specefics informations for a melee carry (safelane) or an offlaner.

What are some goal I should set to myself after each 5 minutes mark (5-10-15-20) in term of LH ?

Edit : Other question, is there a way to see other players LH stats in game ?