HEY you know the basketweave design on this cake should i use a tip #47 or #48 

and also i suck at piping will it be hard for me to do it that straight and even??

That's not really a basketweave design.  Are you talking about the straight ups and downs done with tip 47 or 48?  Either tip would work. It just depends on how big you want the line to be.  If you aren't super confident in your piping, use a tape measure or ruler and mark the top and the bottom of the cake so you have a line of sight to help things stay straight.