Need help with repair

[hondatech]

I am redoing our kitchen and in doing so I need to change some of the plumbing under the sink. I've got all the new cabinets in and am trying to get all the plumbing I can get done before the countertops are put in.
My problem is qest pipes. I have two leaks that I cant seem to figure out how to fix. The first one is at a T (pic1&2) and the second is at a shut-off valve for the dishwasher (pick 3).

At some point Im going to replace the piping for the house but for now I just want to stop the leaks. Please help.