I'm not going to go into more complex redrafting issues like adding side seam pockets or making a fishtail pleat, but I'll go over some of the basic adjustments - namely converting a one-piece pattern to give it side seams (which will allow you to taper it towards the hem for more of a 'wiggle' shape, if desired), and resizing your pattern. These are both really really easy, I promise - don't be intimidated by all the diagrams!
How to trace a pattern
Rather than cut up the original pattern pieces to make alterations, I recommend getting some tracing supplies. You don't need anything more than large sheets of pattern tissue paper (available in haberdashery stores or online) and a pen or pencil. A long ruler is also helpful, and if you have one of those fancy curve rulers then great, but if not then you can just freehand the curves (there aren't many in this pattern anyway).
To trace the pattern, first press it with a cool iron to smooth out the folds. Lay it out on a large table or the floor and lay the tracing tissue on top. Weight it down so it doesn't slip around as you draw (you can get special pattern weights, but I just use tins of tuna!), and trace over the lines. Include the seam lines, darts and any circle or 'notch' markings.
Converting a one-piece pattern to have side seams
This is very straightforward. Start with your initial pattern piece, which will look something like this, with the stitching lines printed on (the dashed lines in the diagram):
You've got the centre front (which will be on the fold, on the right hand side, and the centre back (with kick pleat) on the left. That V-shaped dip forms the hip dart, and will be where our new side seam goes. Simply draw a vertical line from the tip of that V right down to the hem - shown in red below:
Then trace each stitching line as a separate pattern piece, and add a full seam allowance to each.
And simple as that, you now have a pattern with side seams. If you'd like to taper the skirt towards the hem, you can now re-draw the seam lines angled inwards. To take 2" off the total hem, for example, mark a point 1/2" in from the side seam lines on each piece. Then take a straight line from the end of the hip curve down to the hem. Adjust the seam allowances to match, and you're done. Note that obviously this reduces walking room, so you may want to add a little extra to the kick pleat to compensate.
Resizing a pattern
I'll only cover enlarging a pattern, since let's be honest, the chances of you not finding a pattern small enough are pretty slim (er, no pun intended!).
First you have to do a bit of maths. Remember that the pattern is only half the size of the finished garment, so you only need to add half the amount you want to enlarge it by. For example, if you want to make the finished skirt 4" larger in the waist and hips, you need to add 2" to the pattern. You also want to add width evenly all round, so you'll need to add 1" to the front and 1" to the back. Note that my diagrams are not to scale - I've exaggerated the proportions, which is why it ends up looking a little off.
This quick-n-dirty method is not very refined - it's the easiest possible way, which simply adds to the back and centre front. First, draw a vertical line starting between the centre back seam and the darts (we don't want to mess with the darts or it'll throw everything out), and cut along it. As we'll be adding to the centre front, we don't need to slash the front.
Spread the pattern pieces, leaving a 1" gap (for this example) between them. I've also demonstrated below how we add the extra 1" to the centre front by simply drawing in an extension.
Trace over the new outline, and you're left with your new, wider pattern piece:
Enlarging a pattern with side seams is just as easy, and can be done either exactly the same way as above, or simply by tracing the pattern, extending the side seams:
As I say, this is a bit of a cheater method and really only works for relatively small size adjustents (one or two sizes - more than that the proportions will start to look off). So if you need to enlarge your pattern significantly you may want to use a more 'correct' method - Casey has an excellent guide to pattern grading.
Adjusting the waist/hip ratio
To make the hips bigger but leave the waist measurement as it is, draw a vertical line from the tip of the hip dart to the hem, and slash along the line. Spread the two halves apart by half the amount you want to increase the hip size (e.g. if you're grading from a 38" hip to a 42", leave a 2" gap). Then re-draw the hip dart so it comes to a point at the same level as the old one (the blue line in the diagram below).
If the hips are the right size but you need to enlarge the waist, you can do this by making the darts narrower - if you make each of the eight darts (four front and back) 1/4" narrower, you'll add 2" overall; adjust only one out of each pair of darts and you'll get an extra 1".
An even easier method (though less refined) is to eliminate some of the darts altogether: to add 2" to the waist you can leave two of the 1" wide darts unsewn (obviously this only works in even numbers, otherwise it won't be symmetrical!).
To make the waist size smaller, you can either adjust the front and back darts as above (but in reverse, obviously - take in a little extra when you sew the darts to shave inches off the measurement), or make the hip dart a little wider (take the start point 1/2" outside the lines for a 2" overall reduction).
Verifying the fit
If you measure across the hip area of your pattern (excluding the seam allowance, of course), and double the number, it should be your own hip measurement plus about 1" or so to allow such luxuries as, you know, walking, or sitting down.
To determine the waist size, measure along the stitching line excluding the darts, and double. I like my skirts very snug on the waist, so for me this should be my actual waist measurements. If you enjoy breathing you might want to give yourself a tiny bit of ease (half an inch to an inch is usual).