Things You Should Know

...to understand political parties

Never believe what one political party says about another.
Each party wants you to believe the worst about the other. Therefore they will say the worst things imaginable about their competitors.
Never believe what one political party says about itself.
No political party will ever give you a fair view of both sides of the story. They want your votes. They want you to love them and promote them. Therefore they will tell you what they think are the positive and good things about themselves. They will hide, warp, ignore or lie concerning negative truth about themselves. They will tell you what they want you to believe. That is the standard. The standard is not "the truth," but what they want you to think. If the truth is good and positive, they will tell you that. If it is bad and negative, they will never tell you that.
The best way to know the truth about each party is to watch what they do related to what they say, and to think about it.
To understand politics, you must have already decided what you personally believe in life about politics and government in order to keep from being deceived. Test each party with your personal standards.
That does not mean you simply decide "All politicians are liars," or "Politics are too hard for me to understand." That's not thinking. That's copping out. That's running away from the issue. No, you must think. Set your standards in life. Get information. Make a decision. And be always ready to change your mind when you discover something better.
Politicians are most skilled at getting elected, (which is a difficult task).
They are not skilled at business, construction, medicine, medical care, transportation, the constitution, or any other law, if they have not carefully studied that craft before running for office.
Therefore, to trust a politician to know about matters that concern you most is a fool's errand.