Get new ones or clean and mend old ones.
Out with the old and in with the new. Shop for sales and seek out clearance racks.
You can do a few change ups by shortening slacks.....maybe cut off just below the knee to create capris or shorten even more for different length shorts. Shorten sleeves on a long-sleeved blouse by cutting and then rehem the edge. Add lace or other embellishments to various areas such as hems on sleeves, or other edges, and maybe around the neckline. You can dye lighter colored fabric a different color to make a change as well. Changing button can also make a huge difference or upgrade. Hope this gives you some ideas.
Here's some ideas on how to create unique looking shoes: http://www.fashiondioxide.com/easy-diys-to-upgrade-your-old-shoes/