When playing an online casino game such as blackjack or roulette, your best method is to find a basic strategy chart and keep it open in another window as you play. This is totally legal and it will help give you more of an edge.
If, for some reason, you do not want to do this, there are still some basic online blackjack ideas that you should remember to help you through.
Hit/Hold Strategy

Naturally, always hold if you have 17 or higher. Should your hand have a lower value (12-16) then play as if the dealer’s hidden card is a 10. Should the dealer’s score beat yours, for example if you have 15 and the dealer’s up-card is an 8 (a 10 would give the dealer 18) then hit. If it seems likely the dealer will go bust then you should hold, for example if you have 15 and the dealer’s up-card is a 6 (a 10 would give the dealer 16).
Insurance in Online Blackjack

When playing with standard blackjack setup, do not take insurance, ever.
Doubling in Online Blackjack

Doubling hands is for situations when the dealer has a “stiff” card like 4, 5, or 6. You should always double an eleven unless you are up against an ace, and tens as well, unless the dealer has a ten point card or an ace.
Splitting in Online Blackjack

Never split fives, ever, these you should double in virtually all cases. Never split tens either. You should always spilt aces or eights. You can also split nines against everything except a 7, 10 or A.