upto 10L a year is a safe amount, dont deposit more than 50k a week
a person can keep a signed paper ( receipt) with a revenue stamp on it, however limit for this is 10k a day per transaction per client
There are 3 options -
Easy one, file ITR 1 as other income deducting all expenses to run your profession
Little complex one, File ITR 4 as a consultant, show full income ( only 50% will be taxable income under this)
Most Complex, File ITR 3 as business, create bs & pnl
However for cash deposits below 10L per year no one is going to come after you