Very relevant topic as a large working population who started working post liberalization and hence used to much higher standards of living, with no access to retiral benefits such as pension, start to retire over the next couple of years and continue to retire in the years ahead. Being part of an industry partially associated with retiral products, some thoughts:
First and foremost, one needs to assess what would be approximate expenses to maintain a "comfortable" lifestyle, post retirement. "Comfortable" is the operative word here, will vary hugely amongst all individuals and therefore, entirely amongst the family members to be "comfortable" about

. What is also important, however, is to factor in inflation in the range of 6-8%, in the current market scenario and keep an eye on the same till retirement and beyond, as that will be the amount by which expenses will also go up. The idea is to generate regular inflows which beat inflation, by creating a corpus through a mix of asset classes.
There are two main asset classes to create this corpus - Financial and Non Financial. I'll restrict myself to financial asset classes and within financial, products such as MF and insurance and real estate in non financial - audience being the vast majority of salaried individuals.
Step 1 - Build the corpus
Regular monthly inflow amount will depend on the size of the corpus generated, and one has to define this size in quantitative terms based on the "comfort" factor described earlier. This is the most important step, and it would be wise to err in the side of caution and fix a target which is 15 - 20% higher than your calculations. As a guiderail, the calculation for returns on financial corpus should range close to 8 - 9%, based on current market conditions.
In the case of real estate, residential real estate gives a rental return in the range of 3% of the current market value of the property annually. Commercial real estate rentals range between 8 - 10%, BUT are volatile and depends hugely on the location, viability of the building, existing tenants etc. IMHO, investment in commercial real estate is best left to experts.
Between these two (financial and real estate), one has to target to build a corpus which is enough to take care of regular inflows, on a consistent basis, for a period of 25 years at the very least.
For financial investments, some basic tips:
1. Start as early, as possible - NOTHING is as important as starting investing early to generate a retirement corpus. The earlier one starts, the lesser the monthly contribution to generate the same final corpus.
2. Be disciplined - Being regular and disciplined gives a huge impetus for the corpus to grow. It's like a well tuned 4 cylinder vs a sputtering, misfiring engine.
3. Stay long term - That's when the power of compounding kicks in.... Turbo boost
4. The Corpus has to be MEANINGFUL - i.e. It should be of a size that will be capable of giving you inflows on a monthly basis, sustainably. As a ball park, one should not withdraw more than 6% annually, from financial assets to ensure the corpus does not get depleted. So, if your annual expenses are 24 lacs, and say 50% (12 lacs) of this has to come from your financial corpus, the corpus should be minimum 2 crores. The magic here is that if your withdrawals are < 6% of the corpus, the corpus keeps increasing year on year !!
In terms of products, to build a corpus:
1. PF - Yes the HUMBLE PF. The biggest USP - Tax Efficiency and Safety. Please note there is huge difference when we look at Absolute Returns and Tax Adjusted Returns. PF offers it with the unparalleled safety of Govt. backing it. Opt for VPF is your organization offers an option.
2. NPS - low cost, well regulated, tax benefits and a balance by investing both in equity and debt instruments. Offering good tax adjusted returns, NPS has started off in earnest in India over the last 5 - 6 years and is an excellent method of generating a retiral corpus. It is the ONLY instrument which offers an additional tax exemption of 50k U/S 80CCD1B
Both these methods should suffice to build a meaningful corpus if one has a time horizon of 20+ years. In case time is lesser, or one needs a higher corpus, invest in equity MF schemes starting with relatively low risk index funds to at most, a diversified equity fund with an investment horizon of min 5 years. Again the later one starts, the more the value of investment per month to reach the same corpus.
Step 2 - Deploy this Corpus to generate regular returns
So once a meaningful corpus is generated through PF, NPS and Equity schemes, the challenge is to deploy it in products which are safe, liquid and generate adequate returns. Annuities are an option if you are looking at guaranteed returns, but they come with lock ins, so factor that in. FD is another option for fixed returns and senior citizens are offered higher rates as well, with lesser lock in and relative safety. If not many other sources of income, FD's are tax efficient, however they become extremely tax inefficient if income is in the higher taxable bracket. MF schemes are also gaining popularity to deploy retiral corpus and amongst them, liquid category schemes (debt funds with very low portfolio maturities) offer safety, liquidity and reasonable returns. Part of the retiral corpus which can be tucked away for more than 5 years should also be deployed in equity MF schemes as these schemes have the potential to generate much better returns with reduced risks if invested for more than 5 years. Also, if a corpus has been generated through SIP's into equity MF schemes, for over a period of 10 years, it's advisable to retain the corpus in equity schemes (the same if it has given good returns) and do a systematic withdrawal plan (SWP) which is extremely tax efficient (pls do check with a financial planner on the method of withdrawal using FIFO for SIP and then SWP post staying invested for 1 year, and you'll see how brilliantly efficient it is, again considering the current tax structure for equity MF schemes ). Equity schemes have the ability to deliver much higher returns with lesser volatility provided one has stayed invested over a reasonable period of time (5 years +).
Those of us lucky enough to have spare real estate to generate rental income, keep in mind annual maintenance. Capability of the owner to maintain the real estate and maintenance requirements of the real estate are inversely related as age of both increases, so either you have the next gen helping out or you start liquidating and add to financial corpus. I have seen enough examples of properties in posh localities / complexes lying idle for the want of someone to manage it, which is quite a waste of resources. Also, for 2nd gen folks who have gone and settled abroad, the idea of managing a property in India is nothing short of a nightmare, if not the returns a pittance for them.
Also, ensure all financial investments have nominations / second holder and they are well aware of the same - enough cases where the next of kin have absolutely no clue of any financial investments been done.
The other extremely important bit which cannot be overemphasized - Term and Health Insurance. Term insurance is an absolute hygiene and as a ball park, at the very least, cover any debt and potential future earnings to ensure family is protected from any unforeseen eventualities. Spiraling medical expenses means one cannot cover oneself enough and health insurance is another absolute necessity. Just be sure that medical expenses in this country will keep on increasing, and age will force increasing spends. While buying a health insurance, keep a sharp eye on exclusions and stick with better known insurers. Also, maintain a regular annual health check up schedule even as early as 30 yrs of age - we do send our beloved vehicles for annual service - don't we??
Lastly, while all of the above is important, its important to have some sort of engagement post retirement - can be anything - travel, cooking, teaching, pets etc. as again enough examples of idle minds leading to unnecessary despondency.
Hope not too much of gyan for readers
Cheers !!