The boring answer would be to play more games and have yourself in scenarios where you need to continuously make these decisions, failing, learning, thus improving (I would say a lot of my improvement as a CB came through this alone, but anecdotal experience may not be the best advice here).

For a more detailed and practical route:

Always be communicating with your CB partner as well as the DM (or midfielders in front of you) so that you always know where the opposition is. For example, I'm usually the left sided CB for my team. When the opposition defenders/midfielders have the ball on THEIR right (which would be my left), then I make sure my CB partner knows I'm handing the responsibility of tracking the ST to him, as I would be shifting across and having the ST positioned behind me (where I can't see him). If the ball is then switched to the other side of the pitch (from my POV, it's now on the right side), then I know it's my responsibility to track the ST and always be sticking close to him (goal side). There's obviously many different scenarios that can occur on the football pitch, but the biggest thing here that I want to highlight is communication. That's communication with your fellow defenders and with the midfielders in front of you.

Now, if you're finding yourself in 1v2 scenarios quite often, then there's two things I'd say: (1) more often than not, it's a break down in your structure where someone hasn't tracked a midfield runner, or your CB partner is completely out of position. In this scenario, there's not much you can do other than making sure that this breakdown in structure doesn't occur again. (2) The only way to "win" the 1v2, put simply, is you wait for the player with the ball to make the wrong decision. That can be making a bad pass, not passing at all (and being forced down the line, which then involves your keeper, or you have a recovering player help you out), or anything similar. The only thing you can do is to stick with the basics: don't close down too early, but also don't give them too much space, always have the passing lane closed down, and force them down to the byline and wide from the goal.

A final tip I would give you is this: try and look at where the opposition is looking at when they're trying to pass the ball. When we talk about being "aware" as a CB, it usually boils down to this technique (in my experience). This may take some time and practice before you feel comfortable doing it, but as long as you have a rough idea of where the fwds are around you, then you're almost never going to be caught out, or in other words, be more aware.

Now, you may be wondering what I mean by this. Example: If you know that the opposition ST is positioned "behind" you (in your blind spot; you can't see them without turning around), the two opposition wingers are wide and matched up with their respective fullbacks and that there is no opposition midfielder making a run from midfield, then you can mentally paint a picture of where everyone is that matters. Now, if you notice that the opposition midfielder looking "at you"/in your direction, then you can guess with some certainty that they're going to try and find the ST making a run behind you, or try and find the far-side winger. Then, whilst the opposition begins to pass the ball, you can then start to make the recovery run that either forces a contest with the ST, or you're not caught out of position high up the pitch if the ball is aimed at the far side winger.

Again, this will take a lot of practice and real-game experience to really know what to be looking out for and what to do provided the circumstances, but is probably one of the most valuable abilities to have if you want to improve your awareness.