The three main ways to ship to India are carrying excess baggage when flying to India, air-shipping items or sending them by sea using a cargo container shipping company. All three methods have their limitations and advantages. Tips regarding successful shipping depends on what you are shipping and what methods you are using to do so.
If you're taking items as excess baggage on an airline flight, check the carrier's baggage allowance. Rates vary, so shop around and calculate both your personal airfare as well as what it cost to ship your extra bags. Take into account the weight of the bags themselves. Soft bags, such as duffel bags, significantly reduce the overall weight compared to hard-shell luggage, letting you use more of the weight for the items you're shipping.
Air-shipping is good for smaller items but prohibitively expensive for things such as furniture. Ship smaller items you need soon after arrival by air, and ship heavier items by cargo ship.
When shipping by sea, confirm pickup and arrival times for your container. Insure your cargo in case it gets damaged in transit. Purchase a full container if possible. Sharing a cargo container with other customers results in the container taking longer to fill and be delivered.