Early Game

Make sure you buy your early game items. NULL TALISMAN is the first item I would go with two FAERIE FIRE. I assume your teammates will be kind enough to give free tangos. 2 tangos should be more than enough to survive in the beginning.

Why FAERIE FIRE. How I'm going to survive with this?

I usually make my skill build to make sure I have enough regeneration from "Quas". I level up like 3 QUAS 1 WEX and 4 EXSORT until I reach level 8. So my Quas will make sure I have enough regen when required. After my initial items, I'd like to go ahead with Boot of Speed & Hand of Midas or I'd skip hand of Midas and go ahead with power threads and straight go to Scepter. This is very situational and you will have to make an educated guess to make sure you are choosing the best option according to the situation.

Early game combos - being offensive with the invoker in the mid lane is the best way to win and snowball your game. Few combos I usually use during 8-15 min mark to win my lane.

Cold Snap + Tornado + Meteor + Few right clicks (Before Scepter)
Tornado + Meteor + Sunstrike + Defending Blast ( With Scepter)

If you have someone like SF or sniper laning against you, these combos will make sure you get the clicks without much of an effort.

Mid / Late Game

During mid game, I like to create items on the following order

Boots - Travel/Threads
Hand of Midas
Scepter
Blink
Eul
Octarine
Refresher

Your mid/late game impact heavily dependent on your item timing. Early blink with scepter can definitely make sure you are getting crucial kills with right positioning. In terms of combos, I usually use

Tornado + EMP + Ice wall + Meteor + Sunstrike +Depending Blast

to make sure I deal maximum damage during the enemy encounter.

Talent Tree

For talent tree options, I usually go with following,

Meteor damage
Additional Forge Spirit
Cataclysm
Tornado cooldown reduction

The only exception is sometimes I go with AOE depending blast option. This is a very subjective decision and I usually do this to make sure I have a better control against late game-high physical DPS heroes such as PA, PL , CK etc.

I think this pretty much captures my usual invoker build. Hope you guys will able to get some insight from this.

Cheers