I don't worry too much about a little discoloration when they are little.
But to get any suggestions, best to give some detail on what you are doing. If there is some thing to change, it is more likely what NOT to do than something to do.
I think either heat issues or soil is too high in nutrients for seedlings. They will most likely pull through either way. Do you have a light blowing over the tops?
Looks like the drainage is poor and the soil is too hot for that seedling. The tips are burn from excessive nutes whether you gave it to it or the soil already had it in it.