When the money starts to flow...

Be prepared to know what you want to spend your money on before it becomes available.  Have a plan in place.  Most of the time it will be your annual budget, but if you don't have one created at least have a list of what you want.

Keep the list up to date even when the budget is tight.  When the firm starts to free up money, then you will have a plan for the spending that you want to do.  Having a plan helps others to feel comfortable that you are not just spending money on the latest toy. 

Make sure that others have input into the list and that they know where you are trying to go.  When the money is freed up, review your list to make sure that you are spending on the most important items first.  When a firm comes out of a spending freeze, they will most likely be a little skittish about just allowing you to spend on a whim.

By having an up to date list and sticking to your plan, you should be able to get approvals with a little up front work.