Gift bags are certainly a handy shortcut, no doubt about that. Here's a tip, though. When wrapping paper around a box, first attach one end of the wrapping paper TO the box with a bit of scotch tape. That anchors that end, which makes it easy to do the rest. You then stretch the paper all the way around the box, pull it snug and tight, and then trim it with some extra left over, then tape it down. Then fold in and trim the ends. Then tape them down. This will all work best, of course, if you have first precut enough paper to cover the box both lengthways and across, with a bit left over, but not too much left over.

Try it several times with cheap plain brown wrapping paper. Practice! You will soon have it all worked out. Then use the real wrapping paper.

But like I said, just get an adept wrapper of presents to show you how they do it...and imitate what they did. It's a lot easier than trying to follow written directions.