In blackjack do you have to...

Question

place the best before the cards are delt or can you add to your wager once you have seen you cards ?

Answer 1

All bets are placed before the cards are dealt.  Anyone who does not post a bet will not be dealt into that hand.  Under no circumstances can you suddenly add a bet at the end an expect to be dealt in out of turn.  The dealer will usually make it quite clear who is in or out of a hand before any cards leave the shoe.

Once you have your first two cards, you usually (depending on the casino) have the right to split or double down.  When it is your turn you can add another bet, equal to your first, to get one more card.  Or you can add another bet (to the side of the first) to indicate you would like to split the two cards and play two hands instead of one.

The exact rules about splitting or doubling down will vary from one casino to another.

But Blackjack is an ultra simple game, and after watching it for a short time, you'll get the hang of it.

Answer 2

Before the cards are delt. You can double down on hands and split hands after you get the cards,. that adds to the total amount you bet.  

Answer 3

First you must ante up to play. There two scenarios when you can add to your wager

1) You split two identical cards and match your first bet and then play both hands.

2) double down ie double your bet for one more card. Usually only a good idea if your face cards equal ten or eleven.