There is no single answer. You have to know what is going on around you and what ALL the other drivers around you are likely to do, and select the best options to mitigate risks.
If there is someone close behind, you have to assume that they may not stop. But on the other hand, that also makes it less likely that an oncoming driver will turn left in front of you. Even if they don't see you, they'll likely see a larger vehicle behind you.
Make sure the oncoming driver has the best chance of seeing you. If you are in a blind spot to that driver because you are following another vehicle, move to the left of the lane. If you are the lead vehicle, move around in your lane to attract attention to yourself, particularly move towards the left. At the last moment before you reach the intersection, move to the right - basically, take a milder version of the evasive action that you would take if that driver jumped the gun. By doing it automatically, you put yourself further away if the driver does jump the gun a little - and by consciously starting a gentle version of this evasive action, you are already prepared for taking much stronger action if the other driver jumps the gun by a lot.
If there are two lanes in your direction with other vehicles around, sometimes you can use a lead vehicle for cover. This is one of the rare occasions that it may be advantageous to be briefly in someone's blind spot to the right rear. Then the oncoming left-turner can't get to you, without going through the other vehicle first. Unlikely. But be alert to the possibility that your cover vehicle in the left lane may pull an unsignalled right turn, so don't be directly beside them and be prepared to brake at the same rate that they do if you observe them slowing down.
Speeding up to go through an intersection is almost never a good choice ... unless it happens to be a rural intersection with little traffic and you observe a vehicle approaching a stop sign on the cross street. Try to time your arrival so that if they blow the stop sign, you don't both arrive at the intersection at the same time. If that involves speeding up, so be it. At a busy intersection with lots of traffic, speeding up is almost never a good choice. Don't be going faster than other drivers are expecting. The posted speed limit, or a little below, is usually not a bad choice.
Be aware of the dangers of visibly slowing down while you approach that oncoming left-turner. If you visibly slow down, they may assume that you are going to turn. Slow down - Definitely - but don't brake hard unless your internal automatic "emergency stop" alarm goes off because they actually start turning.
If there is someone tailgating, a few flashes of your brake lamp (without actually slowing down meaningfully) may wake them up.
Don't be side-by-side with another vehicle approaching an intersection if you can possibly help it. Keep your escape options open.
All of this should become ingrained in your mind, but it will take some time.
