Hello and welcome, BVeit!
I would like to know if there are anyways to effectively improve my trust for her with lying and infidelity
I'm not quite sure I understand what you are asking for. If she is lying or being unfaithful, or even if she has been in your relationship, trusting her not to do more sounds like a bad idea, not a good one. Perhaps forgiving her is a better place to start before you get to trusting her again?
If you are suspicious and jealous, but don't have any evidence or proof or good reason to believe that she is either lying or cheating, then that's a different thing.
Are the two of you getting into fights/conflicts over these trust issues? Can you describe them?
effective techniques for setting and enforcing boundaries, and ways to help me learn better validation skills for my S.O.
You are in the right place for that. We have a lot of resources for it and also members who have figured out how to make it work themselves, or are working it out.
One suggestion I've got is take a brief pause before you jump into working on validation, and make sure you aren't being unintentionally invalidating. I've found that the tiniest hint of invalidation will "spoil" all your efforts to validate. Plus... .validation is a new skill to learn, and it does take some practice, while not being invalidating (often) simply requires you to shut up, which should be an old and well-practiced skill
TOOLS: Stop Invalidating Your Partner (or the BPD person in your life) Tell us a bit more about specific issues you are struggling with.