Rules before decisions
Count the decks and check dealer soft-17 behaviour, double and split options, surrender and blackjack payout. Small-looking differences can alter the mathematical edge.
Side bets are separate games
A side bet may have different odds and a different house edge from the main hand. Read its pay table independently and include it in the total stake.
Strategy is not certainty
A rules-matched strategy can reduce decision error but cannot remove variance or guarantee profit. Never increase stakes because a losing run feels due to reverse.