There is no fixed basic strategy chart or anything like “basic strategy” in blackjack. Really, it depends on what kinds of bets you want to wager while playing this game. Some are won more often than others but they pay less. For instance, if you would like doing outside bets such as betting on red or black, you will generally win slightly less than 50% of the time in the long run and you will win nearly even odds or $1 for every $1 bet. Then there are inside bets such as betting on single numbers or clusters of numbers. You generally land on these roughly 3% of the time but the payout is enormous. Usually you win about $36 for every $1 bet.
The paramount basic strategy though is to not play on an American roulette wheel. Always play on the European wheel, French wheel or anything with only a single zero green slot in it. This automatically improves your odds by a factor of two.
As for betting, the basic bets you should be doing are the ones with low odds like “red or black”, “even or odd”, “high or low”. These are slightly less than flip-of-the-coin 50/50 odds. The reason you should do this is the payout odds are better than the really risky bets like corner bets, row and column bets and single number wagers. In fact, the house edge on a single zero table is 2.70% on outside bets. This is about as good as it gets. In case you were wondering, the house edge is 5.26% on an American roulette table. This means the casino is taking more of your money much quicker. The basic strategy is that you should always make wagers on bets that have a low house edge.
The next basic thing to do play only for a short time. The casino is guaranteed to win in the long run in every casino game. So people usually win if they quit while they are ahead in the short time. For instance, if you are on a hot streak and come out way ahead after 100 spins, the best thing to do is leave because the more you play, the more the odds are against you and eventually your bankroll will evaporate.
As for betting systems like the Martingale, Labouchere, Fibonacci or something else, these are not considered basic strategy and they do not affect the odds of the game or your chances of winning. These are basically different risk management styles or bankroll management to prevent great losses or to keep you in the game longer. Some are even risky and require large bankrolls, so these are dependent on the style of player and size of bankrolls.