I don't think the open raise size is super important if there is a strategy behind it and you are consistent; a nightmare for you would be to vary you bet size based on your holdings strength. It won't take a rocket scientist to realize that you always bet smaller for value and big on bluffs or some other obvious patterns.
- 3x open raise is usually seen as the standard.
- 2.5x has become more popular among strong players in deep stack poker lately. Daniel Negreanu's "small ball" approach notoriously utilizes 2.5x. However, lower open raises will almost always bring more callers. So 2.5x players (versus 3x) should be more confident in their post glop play; the complicated post flop many beginners make mistakes at.
- Related, many beginners will open larger. Something like 5x consistently to reduce multiway pots played. Here they are "charging" good players from going after them; the bigger open raise also polarizes the ranges so hand reading is easier.
- Another idea I've heard is to open raise your default amount, but then increase it against specific players in the big blind if you really don't want to go heads up against them (like a pro or maybe a reg you have no history with).
- Finally, there is the 3x + 1 bb (or some amount) per limper.
I think all of these can work for your skill level/ play-style as long as it fits your game.