[NP] Which Tax Return to file if I'm both salaried and making money from side-gig?

Hi, throwaway account.

Need some help / advice from you guys.

I am a salaried software engineer in Bangalore, but I'm also getting offers for freelance stuff. I am mulling over a few of these.

One of them seems promising. Three dudes in US are asking me to help bootstrap their startup, and I think I'd take this one.

They are willing to pay me $1000-$2000 for a month of initial work. There's also a possibility of getting more work if they get seed funding.

I am worried about the tax return filing next year. Up until now, I have only filed ITR based on Form-16 from employer. Never had to worry about foreign payment for services provided.

Should I file ITR-4 in 2018?

Or can I just mention it as "income from other sources" under ITR-1?

They are also willing to offer me some equity. Don't know how international equity compliance works, so if any of you have any experience, that would be helpful.

I am sure there are plenty of you folks here who have faced a similar situation. I google a lot (my google-foo isn't that good), and posted in some CA forum, but no reply.

Thanks for the help.

[Note: I am not sure how to add "AskIndia" tag. Mods please help]