If you are salaried or have a constant income every month, you should go for SIP as that matches with your cash flows. For money you got as bonus or proceeds from existing investment or gift, you can invest in SIP or lump sum depending on your comfort level and understanding of market. If you think the market is under-valued (Low PE is one such metric) you can go with lump-sum while in over-valued market (like present situation) you might want to invest in Debt Fund and DO STP (Systematic Transf