This post will contain a tip on how to increase your CPF returns, namely in the form of interest.
One way to earn more interest from CPF is to transfer your extra money, into your CPF Special Account.

Your Ordinary Account currently earns 2.5%, Special Account and Medisave Account earn 4% interest while your normal bank Fixed Deposit earns less than 2% annually.

Real Life Example:
My mum is 49 this year. She wanted to buy a 10-year Fixed Deposit which earns less than 3% per year. I suggested that she put her money into her CPF to earn the CPF interest.

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Based on Normal Voluntary Contribution, the money will be split into the 3 accounts in the following allocation:
OA: 51.36%
SA: 21.62%
MA: 27.02%

Assuming she puts in $1,000, the allocation will be as follow: