Esentially this game is a modified version of bingo, and I think not many serious gamblers would consider this as an online gambling option, but of course tastes do vary.
If this is your chosen game then you probably need to do a lot of research on the different offerings from the various casinos - it can be very difficult to get accurate and reliable published return to play numbers for this game. Without knowing those numbers I find it difficult to play what is then a simple gambling game. I like to know what I am getting into and what I can expect ot get out of it before I commit.
The only possible way to play Keno to advantage is to play for a jackpot, so it might be best to find those casinos that offer a networked jackpot option - this type of jackpot can grow much larger than those jackpots that are run from the house. I do not know of any casinos with those jackpots available right now, as I do not play this game, but I will look into it when I can.
In the true spirit of casino bonuses - from the casino side at least - this is the correct way to use the opening deals that casinos offer you. Whatever about with some other games, there is no point in trying to squeeze any value from them while playing this type of game.
In short, I do not know of one. The best strategy is probably to stay away from this game.
However, if this is your game of choice, then the only real decision that you can make that will have an effect on the outcome of the game is the decision of where to play.
The Return to Player numbers for this game are almost impossible to get, and they vary quite a bit from site to site as far as I can tell.
The house edge too will vary according to the casino that you are playing in. That is true in real life as well as online.
A good approach would be to find sites that have networked Keno jackpots, and to play for those.
Any gambler choosing this game will need to be able to handle the variance, which can be long.
An important point about playing this game is to be careful of the maximum bet limits that will apply while a bonus is being cleared.
Most casinos limit the maximum amount that you can stake on any bet or spin while you have an active bonus that is still to be cleared. This rule is to ensure that you do not bet all of the bonus in one go. If players were allowed to bet the whole amount on one spin, then, while many would lose their bonus money entirely, many would also double their bonuses instantly. The casino is aware of this, and they prefer to enforce the maximum bet rule so that you have to play many games, giving the house edge the chance to chip away at your bankroll.
In a keno strategy that calls for covering many numbers, you may fall foul of the maximum bet on one round rule. Also, trying to cover a lot of numbers on the board could be terms Advantageous play whihc, if you look into the term and conditions, you will see can be grounds for the casino voiding the bonus and any winnings derived from playing it.