What are some ways you use to memorize the ideas behind chess openings?  (e.g. common strategic plans, tactical ideas, endgames, etc.)

You have to understand them not 

Memorizing

Don't memorize. Improvise.

Thanks for the advice.

I understand that playing against other humans, whether OTB or online is best, but would playing an opening position against Fritz or some other chess computer help me memorize the ideas of the opening?

If you have fritz, just use the opening book and learn the moves.

Also I would advise that you don't stick to one opening. It's not good as people easily prepare for you, and you can be 'thrown out' of your comfort zone too easily in which you then have no idea what to do.

I don't memorize, but instead try to understand. Better to choose one opening, try it and see if it works for you, instead of always relying on the analysis of others.

You have to understand the principles behind openings, especially if you play main-line openings. It's not necessary to memorize lines unless you want to play sharp lines and try to win in the opening, which requires lots of daily study time.

If I want to know an opening cold, I read a book, then use chessfeed.com to get the latest games in that opening automatically delivered to me. Saves me having to hunt across the web for them.

Hmmm...i disagree... its also very important to understand the principle when you play sidelines and crappy unsound openings like i do...maybe even more, because there is often less theory about and you will often meet positions not seen by both sides.

They should serve as introductions only to give insight. A player need to immerse himself in it, not just rely on analysis of other players.

You need to know not just the opening but the middlegame and endgames that derive from the opening. A good way to do this is to play solitaire chess. I have found a free program on the internet, Guess The Move, that helps you do this.   

I cannot disagree more.

The best way idea is to find a model player, and look through his games. For example Karpov in the ruy lopez. Then look for themes, which he used twice or more. For example, Karpov really liked the Ba7 idea:

You should stick to your openings. Rather use 1 opening, and really understand it, than using 5 and not really understand them. I used to have no defence to 1. e4, but then I sticked to 1... e5, and it really helped. My opponent might prepare against me, but I don't care. I will understand 1... e5 better than my opponent. Rather have a fight in my territory than a fight somewhere else. The only problem is that I want to play the dragon sicilian, but I must say no, since 1.. e5 is my opening.

EASY! LOL

message me if you need any lines.