If a makes a difference, I usually open with the King's pawn (or, if I'm playing black and my opponent starts with the Queen's pawn, I'll usually counter with the Queen's pawn as well, since I don't seem to know how to use the advantage that can come with sacrificing a pawn at the beginning). Then I either develop a bishop or knight, and typically I try to get both knights and both bishops developed and my king castled before trying to launch any attacks, or do anything else, other defend against any attacks the other person will sometimes attempt during opening.
I'm usually aiming for something like this at the end of the opening stage (though it varies depending on what the other person does of course):
That's simply the type of opening I'm most familiar with and seems the easiest way to take advantage of the principles covered in the lichess course on openings I went through last week.
In order of importance as emphasized in the course:
Winning time is everything
Develop your pieces before worrying about pawn moves
Development lower value pieces before bringing out the queen
Don't move a piece more than once before finishing development
Take space in the center of the board
I'm aware these are general principles/rules of thumb, not hard and fast rules. The course itself gave several examples of when breaking them is actually a good idea, usually because the other person failed to develop their pieces in a timely manner and you're already well ahead of them.
I've noticed my overall skill level improve significantly since I've specifically started aiming for a final opening structure something like the image above (though I'm definitely still a beginner, rated somewhere in the 200s).
However, I've also noticed that, while using this sort of opening strategy and generally following the aforementioned opening principles typically works well when the other person does similarly. But a bunch of times people have beat me at the game, or at least caused me to make several big blunders (even if I still won, because they also made several blunders) by not focusing on developing their pieces immediately, but instead first setting up an annoyingly hard to penetrate pawn structure.
Something like this is what I'm thinking of (though it's just one of the examples I found in my game history; often it gets messier than that, with all/most of he pawns from both sides in a diagonal pattern, blocking each other from moving at all), where I often don't know how to continue advancing my knights and bishops without them just getting captured or immediately attacked (and hence me wasting time retreating) by my opponent's pawns.
I know this is a pretty simple pawn structure overall and I've often seen people play openings like it, but it often still throws me off. Usually, when I do seem to handle it well, it's by immediately trading off several pieces at the beginning of the middle game, which feels like it's not the best way to open the center.
Actually breaking open the center is more of a middle game thing (and the above image isn't even a good of an example of a closed center) to be able that I clearly need to learn how to defend against. My question is, should I be learning how to use these same sorts of pawn structures to my own advantage in the opening, since they often trip me up in responding? Or is it actually a mistake to rely on that before finishing development and it's only throwing me off because I'm still a beginner and haven't had enough practice against those patterns?