Making certain you will recognize what you are trying to sew once you have removed any pins is crucial to your success.
Do not remove any pins yet, and when it is time to do so, know that you will not remove more than one line of pins at a time. That line of pins can be sewn, or you can open up the pin fitting so as not to be double, but it must be closed in some manner before removing another line of pins.
Working at the table, you may benefit from a pencil, small ruler, and smaller scissors.
Examine your pin fitting for any spots which need to be trimmed to 1/2" seam allowance, and do so, measure if you feel you need to. Use the pencil to mark any pin lines where you accidently cut away more seam allowance than you need to have. Use scissors ( long ones ) to smooth seam cut line, to give you a guide to sewing smoothly, if the seam is in fact long and straightish. End seams squarely, do not round off ( seam allowance should not taper ).
You will notch this pin fitting, at a depth of 1/4". These wil be cut into the seam allowance, not the " outty " notches you see on dress patterns. Your notches must be not more than 8" apart on straight seams, and should occur within the first three inches of any intersection. They may occur more frequently on curved areas, or complex intersections.
They must not be equal distances apart, they must vary in distance between them. Why ? Each point of allignment must be distinctive, if it were not, you will misallign. There is no chance you could misallign any part and wind up with an okay fit. In fact, you would not be able to complete the sewing if you misallign any one notch.
Similarly, notches cannot be so frequent that they become meaningless. You may use triple double or single notches in sets, this does not contradict previous sentence.
You may cut away areas of pinned excess that are intended as darts. Leave adequate seam for dart. You may notch between darts if they are far apart. You may mark with pencil ( as opposed to cutting away ) if you intend to fold over excess, or if you intend to dart and not cut .
This did not address fabric that ravels so much notches do not survive. Your seam allowances my not survive either if this is the case, and you would need to have noted that at the beginning, and made choices that would not have perhaps included using doulbe on half method.
We are not unpinning anything yet. Familiarize yourself with this pin fitting, write on it or pin notes as you need to. Later you can skip the notes, but if this is your first, you need to know what your puzzle pieces are: inside back, outside back, inside arm, outside arm, front arm panel, deck, side arm panel if there is one, wing, ect.