Will any changes in lifestyle be suggested during treatment for sinusitis?

Maybe: "allergy proofing your house" will be the first thing. Trying to elimanate allergen "sponges" like carpeting/rugs/stuffed animals/pillows, etc. Unfortunately, sometimes man's best friend has to go as well as cat's. Most pet owners will not let their pets go... So a good over the counter anti-histamine (claritin, zyrtec) is helpful or allergy shots.

Avoid smoke: One of the most severe risk factors for sinusitis and other respiratory infections is smoking or second hand smoke exposure. To reduce chance of infections, wash hands frequently. If you have or suspect dust allergy, using a pillow encasement against dust and removing carpeting may be a good idea. Eliminate mold from home if possible.