If you can't do any combo, you just try to poke a bit or throw. You might also just stand there blocking, not doing anything.
If you do this, you either surprise your opponent, what sometimes make them losing there focus completely, giving you the opportunity to turn around the whole match, or -
If you do this, you either surprise your opponent, what sometimes make them losing there focus completely, giving you the opportunity to turn around the whole match, or -
When you see that you are about losing a match (e.g. it's up to 2-0 for your opponent), just try to finish the whole fight looking as good as possible. That means you do not try to take some vague guesses, what the opponents could do next and you also only do moves and combos that are so easy that you can do them even with your eyes closed.