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You need to set goals first for your account give a dollar target to those actions , track those goals in adwords and raise or lower bids based on how much those actions costed you to achieve per keyword. It could be a view of a key page , signup etc - but a 250 monthly budget is very low unless you have very little competitors.  - Look into google grants if you are a 501c3 non profit it can give you up to 10k of free spend* *if you can spend it - restrictions apply