Hey Anup,

Manmohan and Ranjeet already submitted good answers here. I need only to add some more extra points:

• Post not only Good but Great HD Pictures: Instagram allows us to post square pictures.
• Follow celebrities or popular person in your niche.
• Be consistent: Post regularly funny and user-engaging content
• Tit for Tat: Unfollow those who does not follow you:
• Use the Power of Messaging: Some time messages/ Comment  with a greeting can do the trick. For Example: 'You are looking gorgeous / Handsome in your recent picture '

For more help, you can follow me on Instagram @myselfharish

Instagram is an online mobile photo sharing, video sharing and social networking service that enables its users to take pictures, videos and share them either publicly or privately on the app. Here are the some tips to increase Instagram followers easily in the short period of time:

1. Firstly you need to complete your bio include relevant keywords and hashtags and a link back to your site. This is a guarantee that no one who reads your profile will follow you.
2. Share high-quality photos and videos (image size should be 1080px by 1080px) and add some popular Hashtag(#) related to your image.
3. Search for and follow people who are using popular hashtags like #followme and #likeforlike. Many will follow you back.
4. Start liking and commenting other users and follow them, this the best way to increase followers instantly.
5. Instagram is 90% pictures, it's important not to forget about the power of words. Captioning your photos with funny, clever or unique comments or questions can be a great way to engage with your followers and also gain new ones.
6. Time play the most important role to increase instant followers on Instagram. Research says that its more effective to post pictures at 2am or 5pm (US time) and Sunday.
7. Synchronize all other social media accounts with your Instagram account.

I hope my suggestion will be useful for you. If you have any query you can follow me on Twitter @I_m_ranjeet

Thanks

We all love Instagram. I am highlighting 10 tips you should use to bring more Instagram followers quickly.

1. Use hashtags
2. Hold contest
3. Promote your Instagram account on other social media channels
4. The best time to post photos, according to a research, is 2am or 5pm.
5. Comment on others' photos
6. Ask questions in the captions of your photos
7. Complete your bio
8. Post quality images even if they are less in numbers. Always give quality priority over quality
9. Use popular hashtags
10. Bring Mayfair filter into use.

Please follow the above tips if you wish to increase your Instagram followers.