Hi...
The early signs of gingivitis are swollen gums,bleeding gums, bad breath, receding gums etc.
If you have any of these you should visit a dentist get a cleaning done and then try to keep your oral hygiene good by brushing diligently twice daily, flossing, doing warm saline rinses, taking nutritional diet, rinsing properly after every meal this all will help you in preventing gingivitis.
Also make sure you regularly visit your dentist after every 3-6 months to keep this problem at bay.
Next Steps
For more information consult a dentist online/offline
Health Tips
Keep maintaining a good oral hygiene.