1) Bank FDs or Postal Term Deposits-I think we do not need any explanation of this. If you have an internet banking facility, then I suggest booking your FDs online. The advantage is, it is easy to handle and at the same time, if you redeem online, then the you get the cash immediately in your savings account. Returns from FDs are taxable as per your tax slab (whether they are normal FDs or tax-saving FDs). You can deposit anywhere from 7 days to 10 Yrs. However, I will not suggest using this if your time horizon is more than 3 years. If the goal is more than 3 years, then the above said debt funds or Arbitrage funds are more tax efficient.
Even you can use the Post Office Term Deposits. However, when it comes to facility and service. Post Office lags behind. However, never try to go for Corporate FDs. The reason is, currently the company, which you are going to invest, may have a high credit rating. However, after a few years, if the company not performed well, then the same rating agency may downgrade it. Then is it possible for you to come out of the deposit? These deposits may offer you a higher interest rate than Bank FDs. However, such high return will come with associated risks.
2) Recurring Deposits (RDs) -This is one more type of secured investment. This product is ideally suitable to those who not able to invest a lump sum and looking for monthly investment. Either you can use Bank RDs or Postal RD. Ideally bank offers RD of minimum tenure with 6 months to a maximum of 10 Yrs. Interest received on RD is taxable as per your tax slab.
3) 5-Yrs National Savings Certificate (NSC) -You can invest in Postal NSC of 5 years, only if you are sure that goal is exactly at 5 years from today. You can claim deduction under Sec.80C. However, the interest on NSC will be taxable.
I wrote a post on how one can reduce their tax liability on NSC interest. Please go through and read a below post.
4) Monthly Income Schemes (MIPs) -If you are expecting for regular fixed monthly income, then I suggest to go for Postal MIP. However, I do not recommend you the MIPs offered by mutual funds. The reason is, even though the name of such funds is MIP, but there is no guarantee that they offer you monthly income. Ideally, these funds invest around 10% to 20% of a portfolio in equity and rest in debt instruments (usually of higher duration). Hence, these two points make it bit risky than the other debt funds I referred above. Why take a risk, when you have the same taxation like other debt funds discussed above? Hence, restrict your monthly requirement to Postal MIP or Senior Citizen Savings Scheme (SCSS).