There are two ways through which you may invest in equities and equity mutual funds (MFs) – lump sum investment and systematic investment plan (SIP). It is not just that you go for an SIP because you don’t have a large amount to invest in one go, but even if you have money for lump sum investment, experts would advice you to invest the money first in a debt fund and then switch the money in equity fund systematically through a systematic transfer plan (STP). But in case of fixed return instruments like time deposits in banks or Post Office, no one will stop you from investing in fixed deposit (FD) and ask you to do recurring deposit (RD) instead.