1) Your team has a poor vision around the area
Quite often you might notice professional teams using 5-men smokes and wander around the map looking for a fight. Once both smoked teams found each other they might instantly fall back. But why? If both teams were searching for a fight, why would they decide to fall back? The answer is very simple - they do not have a good vision in the area and they do not think it is a good idea to take a fight in this place.
Vision may have a crucial impact on the team fight result. Having vision on certain heroes may straight up win the team fight for your team. Heroes like Magnus, Axe, or Enigma are good examples. If you do not have vision over these heroes you are always afraid they are going to hit their big AoE spells and you will die. It goes the other way around as well. If you play Enigma, you want to have a good vision over your opponents to hit that one special Black Hole.
Often, if you want to have a good fight you have to bait your opponents to walk into your vision and take the fight there. Whether you are a support or not, start calling to your team to fight around well-placed wards and you are going to be surprised how much it will affect the game.
2) You have nothing to fight for
The fight should have a purpose. If your team has already destroyed both towers in the bottom lane, what is the reason to take a fight in this area? The only reason might be that your team has a superior vision in the area, or perhaps you have a Bounty Hunter in the team, so you can always benefit from making kills. Other than that, your goal is to force fights around important objectives, such as Towers, Barracks, Roshan, or Bounty Runes. The purpose of the game is not to make kills but to make efficient plays that will lead to a victory.
3) One of your cores has a huge amount of gold in inventory
How many times did your team lose a fight and then one of the cores starts spamming that he misses a little bit of gold for the item?
Before you want to force a fight make sure to check inventories of your allies to get the information about their upcoming purchases. No reason to force a fight if your carry needs 1k gold to complete a Black King Bar or other major items.
Dota 2 is a game of economics. One item can have a major impact on the fight. Play around the power spikes of your main heroes.