Ugh its hard!! I have some planned later in my story and hope they'll turn out good. All I can do for now though is firmly establish my main characters so my audience can get to know them and understand what's important to the characters enough so they'll care when they do go through trouble!
When it comes to emotional scenes, I agree that yes, try not to oversaturate with all death and angst and emotion, etc. Balance is key!! I read somewhere once that emotional moments in stories are like money–you want to spend them wisely, be frugal most of the time, and save up the emotion for the scenes that really matter. A couple of examples of successful and unsuccessful versions of this would be [SPOILERS I guess but its so old idk if it even counts] The Fellowship of the Ring movie versus .... the entirety of the last Hobbit movie.
TFotR spent a lot of time building up audience connection to Gandalf from the very beginning, showed that he was a mentor figure to Frodo and the other members of the story, who really relied on him for guidance and wisdom, and when he died it was very sudden and painful, hit very hard, and pacing-wise the audience even had a "moment of silence" where all the exciting action stopped in order to let the audience (and the characters) absorb the emotion of the death. After that brief pause, the plot was able to move forward again, and it continued to effect the characters' circumstances in decisions. In that way, the death had weight and meaning. Also it helped that while there were plenty of other action and battle scenes before, they were mostly brief and not oversaturated and drawn out, and so our emotional dollars are saved and splurged on this particular emotional scene.
The last Hobbit movie, in contrast, was very emotionally exhausting because well for one it started off in the middle of a disaster (the destruction of the town) and then proceeded to put the characters in worse and more and more dire situations, so much that as a watcher i kind of felt numb to the danger the characters were actually in. The audience was expected to sympathize with not just the main characters but an entire town and cast of newcomers who we hadn't even had the chance to really get to know yet. Also the two main deaths in the movie came too close in sequence to one another so by the second main death i was, in effect, emotionally broke and really couldn't care less about what was going on.
whew!! this got long!!! But on a basic level, just identify what characters care about and make them CARE!!! And that will really determine what make them both happy and sad...