When to pick him: My general rule of thumb when picking Meepo is save it for 5th pick if you can, but you can pick it 4th, and that's assuming that there isn't
* 2 heroes with strong bursting capability (Ex, Lina + Lion)
* 3 heroes with strong crowd control (Ex, Axe + Puck + Invoker)
* PA because she just shits on you so hard with her evasion making you miss your attacks, and BKB rush making your poof combo useless, and then bursting you in 3 seconds with her ridiculous damage output
Control groups:I use 1-2-3-4-5 for the Meepos, 6 for the last four (2, 3, 4, 5) and 7 for the courier, and quick cast, having poof on quick cast helps your poof-blink combo so much as you only have to tab-w tab-w or 2-w 3-w etc, without clicking on the location you're going to blink to. And using the 1-5 for me helps the microing in combat as the numbers correspond to the meepos in the top left corner
Items: I go Boots of speed + Tangos into Boots of travel, then Aghanims, then Blink, then Scythe of Vyse, then Skadi for the amazing stats, and then it depends, Ethereal blade can be nice, so can Manta or Diffisual.
Playstyle: (4.9k) I like to play Meepo in the middle lane, rush those boots of travel and use them to farm the jungle, farm middle lane, and keep an eye out for ganks as a good shackle from your offlane Windranger can create the time for you to boots in and snag you a kill, similarly in the safelane a good stun/slow initiation which gives you the time to boots in can easily snag you a kill. In the laning stage for middle lane though, just poof the waves and try to get as many last hits as possible, while keeping it pushed. Majority of mid laners will be able to outlane you, and harass you from a distance so it's easier to keep the lane pushed, stack the jungle, and farm that instead. If properly done, you can have a boots of travel by 5 minutes, an Aghanims by 12, Blink by 15, and be dominating people.
Hope this helped, or gave you some ideas.