Others have already made sensible contributions, so I'll just tell a little story and give a bit of general advice.
One of my earliest MBII memories back in January 2007 was spectating VVerewolf on Cloud City and Korriban. He was by far the best open mode Jedi on the server. I even remember that he was using the Ki-Adi Mundi skin.
To this day, I still have a few vivid images of the gameplay in my mind but the big take-away I got from watching him play was how he kept using movement to not only dodge blaster bolts, but he would use obstacles on the maps to run rings around gunners. I remember him crouching and ADAD to survive against 3 ET/Soldiers and eventually kill them all.
I have an old clip of ThEra that will help illuminate what I mean about movement.
If you really want to learn, you need to closely observe how Masters play the game and mimic them; you also just need a lot of experience (game sense) to read the opponents.
For example, when you've fought plenty of bounty hunters, you'll know the signs that a poison dart is coming. You'll try to manually dodge it by making an erratic movement at the exact moment they try to PD you. You'll try to fight bounty hunters in a place where you can kite them round a pillar to wait for it to wear off. If they have Pistol 3, you'll know the firing rhythm and match your dodges to it, ducking under, to the side or even jumping over it to the rhythm of P3 fire. Lots of details like this that can only be learned by doing, by experience.
You basically need to play the game and learn all the classes. If you know the win condition for a BH, you know what to watch out for. Same goes for Mandalorians and other tricky classes. You have to know how they think and the best way to learn how gunners think is to become adequate at gunning.
Tips, tricks, tutorials and guides are all well and good, but they are no substitute for doing the work yourself by first observing masters, then mimicking them and finally, acquiring a comprehensive understanding of what each enemy class can do to you, and how you can try to win against them.
The main thing most open mode saberists get wrong is positioning when working together with gunners. They either tunnel vision and try to charge the enemy for a kill, or they just get in the way all the time. Get jump 3 and stay out of the firing line so your gunners can shoot at the enemy. Jump on boxes or lamps at the side of corridors to get out of the way while still being able to push stuff.
Do not take gunners cover, do not slow walk around in the middle of the battlefield.
The main corridor on old DOTF is a good example of where these basics come out to play. The noob will run straight down the centre and when he sees an enemy, he'll hold block and start to ADAD in the middle of the corridor, preventing his team from helping him. You fix this by sticking to the sides and making your movement predictable to teammates (no erratic strafing back and forth in front of them). If your friendlies can predict how you're going to move, you can work together properly. You can also frequently find a little ledge on the side to jump up on, or a box or a guard rail something like that, which puts you out of the firing line but still allows you to help your team.
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Jump to the time-stamps in bold to see the examples. For some reason, embedding with timestamps does not work properly.
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A few more examples: this one is 3 rounds on dotf. Watch how I move and work with the team.
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In this clip with the jedi and clone in the corridor, note how I keep moving so that the jedi can't flank me. I try to keep the jedi in-between me and the clone like a meatshield, so the clone cannot help the jedi win. Ideally here, the jedi wants to move to my flank and turn me away 90 degrees or at the very least get out of the way so the clone can shoot or blob, but I try not to let it happen by jumping and moving so he can't pin me down like that.
2:05
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Here is one of my favourites from back in the day. Look at how me and hex tear through their ranks like butter with the teamwork.
Notice how I never stand in the way of hex, which allows him to shoot freely. It's a really good example.
10:28
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Finally, for old time's sake, this clip.
Notice how I hack the window to isolate the jedi and mando in the hangar and how I try to different modes of movement afterwards. First is where I try to turn the jedi away from my gunner so he can shoot him in the back, second is how I try to move back to defend my gunner third is how I move and push the enemy gunner to control the battlefield and isolate engagements as much as possible to avoid being overwhelmed (so the enemy can't use their numbers advantage properly. You use the same principle in 1vX lightsaber duels).
4:45
