The best thing about running an AdWords Account is you can measure and run your campaigns efficiently. Considering a user is running low on budget, I would recommend consider these ideas on 2 stages of your campaign performance:
Stage 1 Creating The Campaign: Do not forget to work on "NEGATIVE KEYWORDS" for your campaign. Add all irrelevant words out there! Especially "How", "What", "Why", "Top" etc. This will exclude the searchers who are just looking for information and are not there to buy the product.
Stage 2 Running The Campaign: Ensure that tracking code is perfectly implemented on your website. Check your campaign performance regularly- understand which keywords are performing well and which are not. Remove keywords on which there are multiple clicks and no or few conversions. Bid more on keywords which results in more conversions even on lesser number of clicks.
It's all about creating and tweaking your campaign according to user mind-set and search behaviour! A person looking for "Why learn digital marketing" is not really planning to join a digital marketing course at that particular search.