Spend your money directly to help VETs pay or buy them and their families groceries, or directly to their landlord or or mortgage company/insurance/car payments or something they need help with, (I'm not big on giving them cash, unless I personally know them) but for don't give anything to organized charities. Charities are in their so called non profit business first to help themselves and mostly/generally only a small percentage goes to help the stated cause whether it be for VETs or whatever.
It's quite easy to find VETs to help - if that's what you really want to put a little effort and money into.
If you approach helping VETs in this manner, 100% of your dollars will go to help VETs and their families.
IME, this ignores the fact that an organized collective effort can be leveraged to provide a much greater benefit to many, than most individuals can provide to a few.