Small budgets fail on Google when they try to do too much. Focus beats spend: a tight campaign aimed at high-intent searches can outperform a sprawling one.
Bid on intent, not volume
Target the specific searches of people ready to buy, not broad terms that burn money on browsers. Long-tail keywords are cheaper and convert better.
Send clicks to a matching page
Never point an ad at your homepage. The landing page should answer the exact promise of the ad, or you pay for clicks that bounce.
Cut losers quickly
Review search terms weekly and add negatives. A small budget can't afford to fund keywords that don't pay.
The takeaway
Narrow, match, and prune. A focused small campaign beats a vague large one.