You may not be writing historical fiction, but your novel has a time and place setting which may well be in the past, however recent. Here's some good advice by author Catrin Collier about research:
THINK OUT what you want to say: - fact or fiction characters – plot – time –place - background - era - the society - and the place (even if it's fictitious).
READ - Old newspapers for the 'feel of the era' (found in library archives). Relevant biographies. Any family diaries or other diaries you can legally lay your hands on.
VISIT - Museums, historical centres, and libraries, particularly ones with 'living history' e.g. tapes made by people relating momentous events in people's lives e.g. a twelve year old boy's first day in the pit, a child brought up in the 1930's as illegitimate.
WATCH - Films from the period. Any period pieces on television or in the cinema. (If possible, British. The Americans are notoriously inaccurate about minor details like facts, costumes etc).
USE - Ordnance survey maps as close to the period as you can get, if setting your book around an actual place. They can save hours of research. Walk the area, take photographs of buildings that existed at the time – note the gaps - check what was there.
If setting your book in a fictitious place draw a map to avoid inaccuracies in the book.
BEG OR BORROW - A song book from the period, and if possible get hold of old records.
RESEARCH - Living conditions. e.g. Don't have people in Depression ridden UK calling out Doctors, going down the dole. If writing about the aristocracy read social etiquette books. The working classes - check out contracts, conditions of employment, wages and the exact buying power of those wages. The leisure activities of the social class of your characters through contemporary newspaper advertisements, parish news magazines, contemporary novels etc.
WORK with your characters until you know their tastes in food, clothes, music, films, sex, etc and exactly how they will react in any situation.
WARNING - this may take the plot down unexpected roads. Go with it - this is creativity working at its best - with luck it may even improve on your original idea.
SPEAK to eye witnesses if possible but treat everything they tell you with caution. Some people have accurate recall and perfect memories, other may remember what never happened.
DON'T write about an existing organisation without doing your research, especially the army, terrorist, Mafia or government organisations. Publishers and agents always send books with a factual background out to an expert reader. Many well-written, well-plotted, publishable books have bitten the dust over lack of research.
DO make an effort to get your facts right, especially concerning weapons, ammunition, cars, computers etc. If you're not sure, don't guess. Consult your local librarian, or an expert.
DON'T write about a scenario that is unfamiliar to you, but will be known to others. E.g. setting a book in the States when you've never been there.