If you see all the colours of the rainbow
There is something called the flop texture, first you determine the suitedness of the flop. Next also how many high cards there are. Are flush draws or made flushes a possibility? There are three situations that can enfold on the flop;
A Rainbow flop is where all three cards are of a different suit.
A flop where there are two cards share the same suit.
A Monotonous flop where there are three cards that share the same suit.
When the rainbow presents itself
Four out of ten flops it will show a nice rainbow. There are no flush draws possible. Only Backdoor draws, it means they need to hit the same suit on the turn and river. This happen four times out of a hundred.
There are two very common types of rainbow flops, one with a high card and one with rags. Rags are cards with value eight or lower. Other types are when there are more high cards, maybe even a pair shows through the rainbow.
If you have hit a weak draw, like overcards or middle or bottom pair, you still have a good chance of winning and with the right pot odds you can even move to the showdown at the end.
One bright colour stands out in the rainbow
The situation is as follow, there is one high card and all are of different suit. This very common flop is useless. hardly any straight draws, no flush draws and top pair or overpair ususally wins. If you got lucky you could even have a two pair. In that case you are most likely to win.
When the case arises that you only have bottom or middle pair, it usually means you are on the winning hand. So raise, and if you have a set slowplay it. If the pot is big, or there are a lot of calling stations (people who will call always no matter their hand) raise the pot. This situation lends itself quite good for a nice bluff or two.
The ragged rainbow or the rainbow in rags
This flop is the worst for the persons that called, or paid for this flop, as they will have high cards only. For the people who saw this one relatively cheap or only limped they could have a nice pair, two pair or set even. This last also goes for the loose players among you.

