A variety of French curves can be helpful for creating smooth curves at the neck, armhole, or for decorative details (a cut-out, for example).

In all honesty, I find these shapes to be a bit overwhelming!  I usually draw a curve free-hand, then refine it with the rounded end of my hip curve.  But these certainly give you a wide range of shapes.

An "L"-square helps to ensure that the lines you draft are perfectly perpendicular.  This is critical when drafting a block from measurements (which we don't do in my method), and at intersecting points (where seams join).

I find this a bit cumbersome to use.  I use my grid ruler to check that my intersections are perpendicular and square.

I use a dot grid pattern paper and manila cardstock  on a daily basis for making patterns.  The dot paper is invaluable for keeping lines straight and intersections perpendicular without a lot of measuring.

And the heavy manila cardstock is a staple in every pattern room for durable block patterns that you'll trace over and over again. 

This bundle with small quantities of both papers is a bargain!

Laundry markers or colored marking pens are used to mark corrections on your muslin dress when fitting the dress. 

I recommend several colors; you'll be fitting your garment more than once, and you can re-fit the same muslin if you use different colors for each correction.

Fabric weights are handy when you lay your paper pattern on your fabric for cutting.  It's SO much easier to use weights than pins!

Pins still work, though, so buy these only if you feel the need.