Yea morello is a nice choice, i remember when ppl took morello and nashor as first items for more shrooms until they got nerfed.
Sometimes ad on hit is more usefull than ap one, but for sure ap on hit has much more dmg than ad. Unless the enemy team is full of tanks. With nashor, rageblade, wits end and rabadon (+morello for example) u will just delete ppl in a second.

thanks for comment mate, and yeah lack of mana is a big problem, but the key is rod of ages or even abyssal mask i think. U know i don't really take morello first because it doesn't bring u much sustain, but if u are sure in your lane why not. But it would be better i think to take nashors tooth in that case. it gives a bit less ap, but a huge attack speed which is essential for teemo.

Thanks for coment, Bonntman!
I think I know why you think so. Teemo is very hard to play mid indeed, But, you know, most mid mages are about poking you enemies with skillshots (syndra, lux, xerath, ahri, veigar, ziggs, velkoz and so on), if you learn how to dodge them properly as teemo (his w helps a lot) you will easily win fights if u get closer. I know thats tough but its real.
The other thing is that teemo mid can shroom map and participate in fights in early to mid game better than teemo top.
Good luck mate.

Thank you FoxOfGreed, I'm glad that you like the guide, enjoy playing! If there are any questions about it feel free to ask.