Clash is one of the most critical part in Dota games. A lost clash means a tower lost. Sometimes a lost clash means a game lost. Observing GGnet.Puppey's picks, it is clear that he is going mostly for early game 5v5 clash and push. Ganking is less in his picks. The reason here is that players have evolved now. They aren't that easy to gank anymore unlike in the past years when MYM would usually go for massive ganks. There are also a lot of surviving mechanisms in today's version. Going for a gank-oriented line up isn't that secure anymore.
There are a lot of ways clash are started but I observed from best Dota teams before and now that there are 5 best way you can start a clash that would most likely make you win the clash.
#6 Ganking a hero and rushing to push towers
Average teams would most likely go for this strategy because of its safety. Once you gank and killed a lone hero and you rush towards their tower, you are initiating a handicap match. If they go impatient and fight 4v5 against your team, you would have a very high chance of winning the clash.
#5 Ganking a smaller group to start a fight
It's difficult to gank a lone hero, specially if they have good supports. However, you can start sa fight by ganking group of heroes that are outnumbered. For example you see 3 heroes at the bottom lane. Your team can all go for killing them right before the opponent come to team up with them. If you successfully killed those 3 heroes or 2 of them, it's difficult for them to win the clash once the back ups arrive.
#4 Using Roshan
One way to start 5v5 matches is using roshan. Just stay at Roshan's lair to make them come. Once they are seen by your wards, you can initiate the fight by picking the best hero to kill first. This is possible because of your vision advantage over them. If you sense that they won't come, just kill Roshan and get the aegis which is another advantage in team fights.
#3 Dewarding and Hiding
One of the best way to start clashes is being unseen. This is mostly effective on their neutral creeps camp. Most of them would be going to farm a lane or go for neutrals, either way you can start the clash by having the advantage of making the move first.
#2 Making them impatient
Once they are going to push, you have the choice whether to charge towards them or to wait until they make a mistake. Rushing towards them will make them have the advantage of picking the target and they'll have the chance to wipe you out. If you choose to wait behind the tower, you have the tower as your team mate making the battle 6 against 5. If they're impatient enough they would march to the higher ground making them so vulnerable. This is the reason of most turning points in the game.
You can effectively start a clash by baiting. Most of the Best dota teams are using this kind of initiator. They bait for simple reasons. One is vision. Next is protecting the key heroes from being damaged. When baiting, the opponent shouldn't know and they should focus fire on the bait landing some of their disables, then you come to save him killing their key heroes first(preferably disablers). Bait should have high tanking ability or escape mechanisms. If the opponents won't hit your bait, make him push a tower then they will hit him.
You can't escape from having clashes that's why I share some of my knowledge from my experience and from watching how professional teams do it. Choose wisely what to use because the type of clash initiator will depend on the situation and your line up.