Well, what roles do you play? If you play mid/top, always call missing using 2 or 3 missing pings and ping "be careful" about twice near bot lane if you saw your enemy going down toward bot/teleporting. If you're jungle, get a pink or get the jungling item that gives you 2 charges of wards and ward bot lane so they have better vision. Obviously gank when possible.
Just checked, seems your Taliyah, so definitely do the things I said. Concerning them dying in their own lane, you have little to no control over that. Out of your past 5 games, it looks like 3 of them were bot lane feeding pretty badly. I wouldn't worry too much. As you play more people get better.
This one's a bit risky, but if they start dying more than 2 times, tell them to just farm in lane for a bit and chill. Empathize with them that it's frustrating to lose lane like this and they'll probably miss out on CS because they'll have to play super safe. Heck, even if they play super safe, if they get 4-manned bot lane and tower dived without warning, you can't blame them. They'll be salty AF. But just tell them nicely that they need to just farm up and play safe as much as possible even if it's frustrating. Maybe bringing them back to reality will stop them from trying to constantly fight people when they won't be able to win (i.e. feeding).