x2 on what Trevor said..
Once your hitch is connected and secured on the ball, raise the tongue jack back up a goodly bit. The more weight that is on the tongue jack, the easier it will be to get the bars/chains connected, and the safer too, as you don't have to use so much force to get them up and connected. Plus this allows you to get them tighter.
After the initial setup (which as noted works best when the TT and TV are on flat ground) you can hitch it up on an angle, but it will be harder to get one bar side up than the other if it's uneven.
2012 Flagstaff V-lite 30 WTBS
2011 Ford Expedition
4 kids and a hubby & never enough time to camp!
2011: 17 nights 2012: 26 nights 2013: 46 2014: 20 2015: 16