Odds and EV

I have read the strategy articles and checked out other websites on the subject of calculating odds and expected value. I have a pretty good understanding of how to come up with the numbers, but it seems to take me too long to calculate them during play. Does anyone have any tips on quick ways to determine these values, especially EV, since it takes me the longest. Thanks for the help.

The rule of 2 and 4 may help

Take the number of outs you need to win say 9 left in the deck for a flush draw

if there are two cards to come you multiply by 4 so you are 36% to make a flush with two cards to come

The river is the same only by 2 instead of 4.

the perctages are approximate but much quicker than the exact numbers.