When it comes to choosing the right top for your body, there are a few key areas to pay attention to.

1.Where the seams of the armhole sits on the shoulders
2.The closure seam on the torso. (whether it be at the center front, center back, or sides.)
3. The length of the sleeves, and the amount of space from fabric available or lack-there-of around the biceps and forearms.
4.The length of the torso, and the amount of space from fabric available or lack-there-of.
5.Neckhole- if the drop of the neckline is too low, or if the neckline is too wide.

these are the 5 main factors that you should look out for when fitting your tops.

office-clothes_ill-fitting.jpg picture by Deathbutton
You want to avoid the squiggle effect when figuring out whether a dress shirt, cardigan, or any shirt that may have buttons as the closure. This is the best way to know whether something fits you, even if you plan to wear it unbuttoned and left open- wearing it with the buttons entirely closed show you whether the size you've chosen is correct for your body, afterwards- how you dress it is entirely up to you!

Linda Fitted Dress Shirt
Take note how the dress shirt falls smoothly onto the body, nothing is pulling or puckering. The shoulder seams are sitting perfectly on the "ball" of the shoulder, and isn't sloping too far down towards the arm, nor is it too tight and pulling towards the neck. The fabric around the torso, waist and hips are well fitted- There is no excess fabric hanging loosely about, and it matches up where the curves of the supposed waistline determined in the shirt is with the actual waistline of the body.

dressshirt02.jpg picture by Deathbutton
Notice the curve of the back is smooth, the dress shirt doesn't have any excess fabric bunching about ( which would be a problem when you plan to tuck them into pants or a skirt, it will start shifting back out on you)

shitfrnt.jpg picture by Deathbutton
Necklines generally should fit on you in a way where they wont be sliding off, or have you fidget with constantly. The general rule is that when they start to pucker either at the front or back, do not sit flat on your collar bone or back of neck, and overall doesn't feel comfortable- then it is the wrong fit. I know that there are some intentional designs that have the "wide neck" look happening, but even those have precautions you should take, just because it is a wide neck design- doesn't mean its the RIGHT wide neck design SIZE for you. Unless it's meant to fall off your shoulder, it's too big for you.

lnadevteesha.gif picture by Deathbutton
The shirt shown above is too loose, the neckline is very wide and rippling all around. Here you can see that the bra is borderline peeping out. The hem of the shirt is a tad too long as well, unless you have a personal preference of wearing shirts pass the hips- this one sits well below the crotch area, causing it to start looking a little sloppy.