How to Tailor Shirts Yourself (and a General Dart Tutorial)

In the U.S, it is difficult to find clothing which fits really well. Dress shirts are one of the easier off-the-rack garments to find in a true slim fit, but even that is somewhat problematic. Fitting the arms, shoulders, chest and back is actually really easy. However, very few designers create shirts which will also contour to your waist as well. This is even more of a problem if you have any kind of a V-taper.
So what do you do?
A) You can buy the shirt anyway and not give a sh!t about some puffiness by your waist when you tuck it in.
B) You can take it to a tailor to add darts or taper the sides.
Or, C) you can search online for some inexpensive custom made shirts (there are some decent ones out there, but I will not list any by name because I'm not getting any reimbursements).
A) is somewhat pointless as you are already taking the time to find something which contours to your form, so why halfass it by neglecting how sloppy it appears by your waist?
C) Can be inexpensive, but it's pretty time consuming. You will have to measure yourself, look through different websites to find your best option, sift through all your different fabric patterns or shirt features to find which suits you best, then wait 2-4 weeks for it to be made and delivered to you. Not really all that bad, but it's still fairly inconvenient. Especially since most people do not even know how to properly measure themselves.
So out of all these options, we are left with B as the most reasonable.
However, did you know that measuring and sewing darts is actually very simple if you have even a basic ability to use a needle and thread? I'm sure you can figure where I'm going with this, a B.5, sewing the darts yourself.
Don't be intimidated though, as I will give you some basic instructions as to how you can do this by hand with a basic sewing kit from your local pharmacy without the necessity of a machine (though, admittedly, the speed difference is astounding). I will try to type up some steps as simply as I possibly can so any of you can follow these instructions.

Step 1: Put on your shirt. Button it down fully

Step 2: Look at where your shirt is the baggiest. Reach to the back of the shirt and squeeze in the fabric until its look at the front pleases you. This is where you will draw the horizontal lines of your initial dart. Place a pin to hold it in place when you release it.

Step 3: Measure the excess fabric. This is basically what you want to take in with your dart(s). Note: Use the metric system when you measure. No, I'm not a commie bastard, but centimeters are a lot more precise than inches. 

Step 4: Begin to measure out your darts. You will generally not want each dart to measure wider than 4-5 cm each, as taking in this much fabric will require the dart to be very long if you don't want it to distort the shape of the shirt. If this means you will have to sew 3, 5, 7 darts, then so be it. Your initial dart should be dead center on the back of your shirt. Since most dress shirts tend to have a slight undercurve (like a u shape), find the point where it hangs the lowest. This is where you will draw your first vertical line.

Step 5: To draw your darts, make one horizontal line evenly crossing the vertical line (for instance, say your dart is 4 cm wide, your horizontal line will hit the vertical line at 2 cm). All markings and stitching will be done on the wrong side of the fabric (the wrong side is the side which touches your body. The right side in the outer, visible side of the fabric). After this, connect the edges of the vertical and horizontal lines with diagonal lines so that it looks like a diamond.
Note: The wider the h line, the higher the v line should go, as the fabric will actually fray out if the stitching doesn't "disappear" into the fabric gradually. The lower line isn't as important.
It should look like this picture : (I made the h and v lines much thicker than they need to be just to accentuate them. You will just make a thin line in practice).
 

Step 6: fold the fabric at the v line so it looks like this.

Step 7: Make short, straight stitches on the diagonal lines.
Here is what it will look like on the side you are stitching.

Here is what it will look like on the opposite side

Step 8: Keep stitching until you hit both ends, and your dart is complete. If your shirt billows out, raise the dart higher and make sure you are taking in almost no fabric as you get closer to the edges. Remember, the stitching should eventually "disappear" into the fabric.
Keep adding darts to different parts of your shirt to improve its fit or to add a bit of a design.
Have fun!