An "engage" button for battle // No troops are preselected before battle
[Engage button] When the timer is ticking until the battle starts, a button to press before you are allowed to drop troops would help with players who accidently drop troops when trying to hit 'Next' or when sliding the screen.
[No troops are preselected before battle] In battle your first troop is preselected, making accidental troop dropping more likely, so maybe there should be no troop preselected.
(Will add photos for reference)