Most tourists, instead of directly flying to Osaka, reach Narita at Tokyo and then either take the subway or the bus to Osaka. This is the cheapest option. However, Osaka even can be reached by air. Many flight services like AirAsia and China Eastern are available for direct flights to Osaka.
For Indian tourists, it is advisable to first land at Narita International Airport, Tokyo, and then either take the subway, bus or a car to Osaka, for it is much cheaper to do so.
By air, Osaka has limited connectivity compared to other Japanese cities, but is connected by two airports- The Osaka Itami Airport and Kansai International Airport, the latter of which is better connected internationally, while Osaka Itami is better connected domestically.
Cars can also be rented, but taxis can be a little bit more on the expensive side.
Japan has a very well-connected subway rail system, which connects Osaka to almost every other Japanese city. Subway cards are also operable. However, they are convoluted, so it is advisable to carry a map or an accurate mobile application for navigation.
Osaka has a bus system running within it, and outside it. Bus passes are available, in many denominations. There is also the Osaka One-Day pass which covers all bus travel expenses for a day. However, the subway system is much easier to use.
Ferries connect Osaka to other islands in Japan.
The subway, the bus, and railways are the best modes of transport. 24- hour passes can be procured for heavy travelling, while IC transferable storage cards can be used for payment.