Kunal Bajaj is CEO & founder of Clearfunds.com said that if you’re confused about how much to save and invest from your overall household expenses, just follow the 50–30–20 rule of thumb. “Spend 50% on necessities (rent, food, transport, education), another 30% on things you want or enjoy (“discretionary expenses”) and save the remaining 20% for the long term investments,” he said.