None of the below factors alone determine the fundamentals of any business its the collective approach  

Do you know the promoters of the companies where you are investing ?

Check their Credibility & Past experience in business.

Is there a monopoly or Entry barrier in the business ?

Strong Moat, Monopoly, Duopoly or Dominant position, Some Entry barrier in business is highly recommended .

How is the debt on the books of the company ?

Debt free or virtually debt free, Asset light businesses are recommended .

How is the reserves ?

Reserves should always be more than the debt on books .

Now check the FREE CASH FLOWS

The most important Parameters of fundamentals is that the net profits are reflecting on books as positive free cash flows.

How is the sales & net profits  ?

Sales & Net-profits should always be growing Year -on- year .

Look for Futuristic business

Industry should in be growing phase .

How many outstanding shares ?

Preferably less than 500cr. More the outstanding shares of the company lower can be the EPS.

Did you check the ROCE ?  ( Return on capital employed )

To understand the utilisation of funds overall raised by the company - Preferably more than 18%  ( Other than banks & NBFC )

Whats the ROE ? ( Return on equity )

To understand the utilisation of funds raised by equity - Preferably more than 15% ( Other than banks & NBFC )

Check the PE ? ( Price to earnings )

Let's not go into formulas - Preferably PE should be less than 150 on higher side for a fast growing company OR Simply compare it with Peers .

Have you checked the shareholding pattern ?

Majority with Promoters, FIIS & DIIS signifies strong share holding pattern. Check the change in shareholding pattern every quarter .

Is the Promoter holding pledged ?

If the promoter has pledged their shares more than 10% on higher side it's time to exit . The best example will be 0% pledged !

Whats the face value ?

FV of 10 may possible results in split resulting in extra shares to the shareholders .

Have you checked the capital expenditure plans ?

Imp. to know company plans for growth eventually increase in sales & Profits .

All the above information is available on NSE & BSE