Both the PHB and the DMG will give you pointers on what researching spells needs (either existing spells to add to a spellbook when levelling up, or brand new homebrewed spells). Basically the wizard needs access to a library and other sources of information to complete the research.
However, if you want to add some more fluff to it, you can look at the whole thing as a typical nonmagical scientific experimentation process.
Asides from literature on the matter, impose the need for a lab (ex.: for researching the appropriate material components and reagents), have the wizard rent, use or go to some area where they can practice the gestures needed for the completion of the spell (ex.: a desert, a free room in the local arcane academy).
Also, the magical experimentation process is bound to fail at some point (i.e. mishaps), so a safe environment may be needed to keep innocent bystanders, and the wizard himself, out of harms way.
Just my 2 cents...