My husband and I are new to baking and decorating cakes. We've gotten really good at doing round cakes but recently we were asked to do sheet cakes (in addition to two smash cakes) for a double 1st birthday for my friend's son and niece. We made our first sheet cake over the weekend and it was definitely challenging to get the corners straight but somehow my husband managed to do it nice and straight. Any tips or suggestions to do it in less time and not lose the corners would be great. Thanks in advance :)

I found this from the archives of the basement of the internet...B. Keith Ryder has demo'ed this method a bunch of times, if you scroll down a few posts you'll find his post describing how to do it. You basically use one spatula held vertically as a guide as you put icing on using another spatula, then pull the guide one away. I tried to look up his website but it looks like he isn't doing cakes anymore so there was no link to any photos of how to do it. http://forums.egullet.org/topic/70728-demo-sharp-edges-on-cake-layers/

Thanks!! I tried to find some videos on youtube but didn't find any by him either. 

I found this video:

Those blasted corners were my personal bugaboo when I worked at the grocery store bakeries.  I'm somewhat dreading the day I get asked for sheet/square cakes.....

Thanks @BakerBlackCat  that sounds like the video the other poster was talking about!! You all are sooo awesome!! I sent the link to my husband and he is watching it now :)