Whew...that's a big question. It's so hard to know where to start and what you will use. I'd start with a straight one, a L one, and maybe some circles. I been adding as I go...I've finally decided to add a few from the Gadget Girls.
https://www.thegadgetgirls.com/ They have some beginner packages that might be useful. I also have some from Quilters Rule -
http://www.quiltersrule.com/ that are nice. I also have a few from DeLoa... they have a great Little One that I like and the Castle one.
http://www.deloasquiltshop.com/deloa...eoneguide.html
Also one I love - Line Tamer. This one works great.
http://www.fourpawsquilting.com/pages/template.html So lots of options.