The cheapest way to freshen up your wardrobe is to just change what you already own. Even the cutest peices can start feeling a little stale and boring when you've worn them fifty times. Altering and embellishing can make something old feel and look new (or at least new to you).
A little altering can make an amazing difference. Simple alterations like hemming or adjusting fit are pretty easy if you have some basic sewing skills. Marisa at New Dress a Day makes quick and easy alterations and turns $1 horror shows into adorable outfits.
The shirts my job provided were a lovely square shape, so the first order of business was to take them in a bit. (Check out this tutorial at Fashionomics.) Several of my thrfted skirts are altered too. I've found some great ones for just a few bucks and all they needed to be cute was a few inches taken off the hem. My favorite dress started life as a $2.50 thrifted kaftan. (Side note: dresses with giant peacocks on them are incredibly versatile, don't let anyone tell you differently.)
If the fit isn't the issue so much as terminal boringness then it's time to embellish. I figure the best way to distract from a boring polo shirt is with interesting and unique pieces. I can exercise my creativity and save some money towards the start up costs for my future small business (where I can wear what I want). Need some ideas?
Add some details to your basics. Plain blazers are plentiful and cheap (about $5) at thrift stores, and I'm loving blazers with contrast edging.
How easy would this be to do with some bias tape? I have a cord blazer that I think will look awesome with some scholarly elbow patches and floral print edging. Grab a bias tape maker and get to work! Bias tape could also look cute along the edge of a skirt, around the arms of a blouse, or to create stripes on a jacket sleeve or pant leg.
Appliques are an easy way to add character and interest. Most craft stores will have a selection on iron on embroidered patches. Check out Etsy for some more original options. I found these these awesome skull patches. If you want a little more glitz, go for beaded or lace appliques. Check if your local fabric store has a bridal section, or look online. I already found some I want at sequinappliques.com, including a sequin stegosaurus.
Also look at thrift stores for uniforms with patches or old formal dresses with applique pieces, the whole piece may cost you the same as a new patch would. If you want to be able to change it up a little, sew or glue a pin back or two on. (This will extend the life of you applique too, since you can take them off to wash your clothes.)
New buttons, one of the cheapest and quickest ways to change the look of an item of clothing. . If you need some instruction on sewing buttons, check out this video from Threadbanger. Take your garment with you, or snip off one of the old buttons to take with you for size. I found some disgustingly cutesy little buttons on Etsy from sellers Mr Walrus and Thai Fab Shop. You can also make your own buttons with a covered button kit and some cute fabric. I made a little skull button with a teeny piece of my embroidery.
Find yourself a stud or two. A lot of interesting looks seem to be all about mixing cute and masculine, and I'm all about metal studs for the perfect punky touch. You can grab some at studsandspikes.com, a bag of 25 will run you less than $5.00. (You can grab a kit to set them, but I distinctly remember just making do with pliers as a "rebellious" teenager.) I'm thinking floral wristbands with metal studs? Studs and chains from the hardware store could add some interest to plain boots.
Embroidery is easy, cheap, and you can even take it with you to work as a little lunchtime craft therapy. Grab a hoop and head over to Sublime Stitching or Mr X Stitch (where you can get my Internet meme embroidery patterns, by the way). You can also grab free patterns at Needlecrafters. Beads or charms would make it even more interesting.
I'd love to hear your ideas for embellishment.