Effective odds are the odds you get from the pot with more than one card to come. You are a 1:4.22 underdog to fill a four-flush on the next card, but a 1 3/4 by the river. This doesn't mean you should take less than 4.22:1 on your money on a certain street because unless you are all-in, you'll have to put more money to see the next card.
For example, the pot is 50 and you are heads-up in a LHE game (10/25). You have a four-flush on the flop. You calling the first street is correct, but only if:
a) You only peel one card
b) you have reasonable chance to have the best hand right now and still have it on the turn (in order to stay in). Let's say you have paire a J and the flop is two of your suit.
This is because on the turn, your opponent will likely bet again, this time 25 in a 70, meaning you will have put 35 to win this 70 if you hit on the river. Not nearly enough to call in the first place if you only have flush outs and intend to go through with your hand. This is also why raising on a draw is profitable since we are more likely to get a free card on the turn
So, in order to calculate effective odds, add all the bets you will to call and compare that to the size of the pot on the last street (we pay 35 in the example, to win 70). Since our opponent is not likely to pay us off on the river, we cannot add 25 to the pot, and even then, our odds would be 60 to win 115, wich doesn't tally to 1 3/4:1.
In NL, implied odds often are way more in line with the correct strategy, especially with limpers and/or many callers since the bets increase a lot in bewtween streets and the odds of getting payed off big balances the small mistake of peeling on off.