Deseret Industries donating gal myself. However, I do love the convenience of the pick up services of other charities.
But... did you know that you only can deduct around $500 on your taxes w/out receipts of donations but you can deduct up to much more if you keep good records? You'd be surprised at what your old clothes are valued at.
Here is a LINK to a Salvation Army based Valuation Guide for your donated goods. For each donation drop you do you'll want to record each item in this spreadsheet and then either print it and staple it to your donation slip or save it in a tax year folder on your computer. I have a folder in my documents that is labeled TAX. Within it I have folders dated by year. If I have anything that I need to save for taxes whether in the past or in the future they go in here. I also have hanging files labeled TAXES also with files labeled by year behind.