There is no one size fits all approach to this. Planning your budget means knowing what you can afford.
How much loan you are eligible for will depend mainly on your credit rating and salary that you are drawing. You need to break down the parts according to the unit that you have. The market rate on the things that you need to renovate. The furnishings that you need to buy. And last comes the things that you want, but can live without.
The above steps are not financial advice. These are merely suggestions by someone that has been in the industry since 2016, and have seen what it can do to new homeowners especially if they start wrong. Always plan your finances ahead.
Please do reach out to us when you plan to buy a unit, and plan to gauge the renovation costs before commiting. This is a paid service and a quote can also be provided should you need one.