How to play offlane
If you go as offlane techies, the first thing you need is health regen until you get Soul Ring.
You get Blastoff first because level 1 Prox mines do not kill anyone and will leave you without mana. Better get Blastoff first so you can gank with someone and get first blood at runes, or in the lane. You can also use the insane starting regen to deal damage to their carry.
At level 3 you should have lvl 2 prox mines and sould ring. Start mining the sideshop and the side trees to protect yourself from ganks and kill someone if they dear to go in.
Also a good idea to put mines at the shrine, since they might try to gank you from there as well. Make sure the pattern of Proximity mines is in a triangle. This ensures maximum damage.
There is no point in skilling Remote mines until later on since you will not have the mana needed, and Proximity mines will deal more damage at this stage.
Mid game you should be roaming and using the Blastoff+proximity mines combo to deal massive damage and help your carry farm.
Once you get remote mines, start mining the lanes, and for the love of god, if your team is owning, put remote mines on the enemy side of the map, don't play defensive if you are wining.
You should also use proximity mines to farm jungle whenever you have the chance, you need level 25 to transition to a righclick techies.
Late game you should not be using blastoff for anything but denying yourself and you should mine Proximity+statis under you and wait for their carry to come to you. If they come, they get rooted, damaged and you should be able to rightclick them down with the level 25 talent.
If you reach level 25, your goal is attack speed. Focus on that. Bloodthorn is good cause it gives you the silence, the truestrike and the extra damage and attack speed.
Mine defensively from time to time, but focus on helping your carry end the game.
How to play support techies
Its best to trilane safelane with your carry, hide in the trees and blastoff on your enemy to allow your carry to farm heroes. Make sure to always have mana for blastoff and tp scroll.
Get lot of mana potions to proximity mine around your carry to ensure his safety.
Once you have remote mines, use them as wards for vision until you have Lvl3 and aghs or to snipe some damage from a distance.
Your job here is to mine defensive and offensive around your carry to ensure his safety.
If you are on a disadvantage, mine base and wait for them to initiate. Also mine offensively on their map if you have the advantage.
A common combo is Blastoff+proximity mines, force staff yourself and remote mine on the target. It may not kill a carry, but it will help your carry get him.