Oxygen and Greenhouse Gas IntroductionEdit
It is possible to generate oxygen from silica and water, which are the primary components of Titan. By introducing enough Oxygen, it may be possible to allow humans to breathe on Titan without much modification, besides adding an immense amount of heat through greenhouse gasses such as: SF6 . However, SF6 poses two main problems. Firstly, Fluorine, the main component of SF6, is relatively rare. Also, SF6 freezes at −64 °C, whilst the mean temperature of titan is -179.15 °C. That means that any SF6 added without warming Titan previously, would fall down as snow. Another possibility, is to add NF3 instead of SF6. It is somewhat easier to do, as the atmosphere of Titan is almost entirely composed of nitrogen. Any F2 released into the atmosphere would react with N2 and form NF3. However, that does not eliminate the need to search for fluorine. Unlike SF6, NF3 is not inert. Also, NF3 is liquid at -179.15 °C.
Titan's crust is completely ice frozen to the point where it becomes similar to land. Underneath this is potentially a liquid ocean, and underneath that is an ice mantle. If the temperature raised to allow for liquid water on the surface, either floating platforms would have to be established, or potentially the establishment of artificial continents. The latter would be very difficult as you don't get to silicon or any other similar substance till you get to the core (which itself is silicon oxide).
This would also rule out importing of all terrestrial lifeforms as well as the vast majority of aquatic ones which somehow rely on the sea floor (unless you build an artificial one).