Steps 1-3: Take the jeans you want to alter and turn them inside out. Take a pair of jeans you like the fit of and lay them on top. These will act as a benchmark for your alterations. Pin along side of the benchmark jeans. Go as far up the leg as you deem necessary. I pinned until a few inches above my knee. After pinning, you may want to try the jeans on (you can leave them inside out) to see if you like the new fit. Adjust the pins as necessary. Now, sew along the inside of your pin line (if you sew along the outside, it may be too tight). This will create a new seam. Be sure to extend your seam to the inner edge of the pant leg. Repeat on the opposite leg. When finished sewing, cut off the excess fabric on the inside of your seams. Turn right side out. Now the fun part begins!
Step 4: Try on your newly altered jeans. With a pen or marker, mark where you would like the destruction to be. Generally, you want to mark higher stress areas where there would naturally be more wear (ie., knees, pockets, back pockets etc). Take the jeans off and with a scissors cut 1-2 inch strips between the areas you want to destroy. Be careful to only cut through the top layer of denim.
Step 5: If you look at the back of one of the strips you cut, you'll notice that jeans are made up of blue and white strands woven together. The white runs horizontally while the blue runs vertically. The idea is to leave as many of the white strands intact.
Step 6: Use your tweezers to start pulling the vertical blue strands out. You'll have to pull the first few individually, but as it gets a bit looser you may be able to pull 2 or 3 strands at a time. I found it a bit faster to use the tweezers to scrape and pull the blue strands sideways (instead of up or down) out of the weave.
Steps 7-8: Repeat step 6 for all of the areas you wish to destruct. This is a bit of a time consuming process, depending on the size of the area you wish to distress, but can easily be done while catching up on Netflix or listening to music.
Step 9: Admire your handiwork and then show off those bad boys to all your friends!