How do I use Datastore's effectively without error?

In my game, Spinning Thing of Doom 2, people complained that, at random, their data was deleted. I made an update a few hours ago, hoping to fix it. As of now, I have 3 values that go inside the player; Cash, Points (in leaderstats), and Purchased (a string value with the inventory of bought items).

function decide(player,leaving)
if leaving then
if not set(player) then
update(player)
end
else
get(player)
names:SetAsync(player.userId,player.Name) -- this is set up such that a backup store is created
end
end

game.Players.PlayerAdded:connect(function(player)
for i = 0,60,.03 do print("getting stats...")
wait() if player:FindFirstChild("leaderstats") and player:FindFirstChild("Purchased") then decide(player,false)
break end end
print("loaded")
end)

game.Players.PlayerRemoving:connect(function(player) decide(player,true) end)

This is the logic behind the saving. Then I have a few "shortcut" funtions called get(), update(), and set(), each with player as its argument. The for loop at the starts waits a full minute of trying to load the stats of the player, but I have no idea if thats a good idea or there is any method unknown to me that would make life easier...

Sorry for the giant wall of code and text, but I need to know if there is a more... dynamic way to make stores more solid.

Thanks! ~Tiger