As we have seen a worst weekly decline in the stock markets this week. Markets are on the edge of break off on the lower side and see a significant downside. Factors that might weigh in

1) Greece Election Outcome
2) France Elections and its relation with Germany
3) Global markets' negative sentiments as US markets were only holding up its gain and started loosing it now.
4) Steep Decline in Oil Prices due to loss of confidence in economic recovery
5) "Sell in May" sentiment effect

Don't try to play markets on a long side and it is advisable to sell on rallies. Also see how to trade Nifty next week here