being decent at baseball really comes down to knowing the fundamentals and being generally familiar with the basics of the game. for most people i've played with, baseball is a hard game to just pick up and play without a good amount of experience playing it. many sports rely more on sheer athleticism, but baseball is really all about technique and getting to the point where doing things the right way become habitual. but that's not really ADVICE. that's more the way it is.
one of the better things i did to get good at baseball when i was younger was to watch a lot of baseball. not just casually watch baseball, but really study what they're doing and try to figure out why they're doing it. i've found this particularly useful when hitting. i would watch the way players hit and attempt to emulate their swings, or at least parts of the swings. of course, this was more when i was much younger, but this is the way i can do it, and i can hit baseballs out of most stadiums now.
but in terms of hitting, one of the best things most beginners do not do is use their hips in their swing. most people i see just go up there and swing their arms, but do not comprehend that when you start your arms into the swing, half of your power comes from your hips. as you bring the bat from the starting position in an attempt to make contact, the rest of your body needs to be in motion. in the time before you make contact with the ball, your entire body needs to be at work. this is extremely general advice, but it's something to keep in mind when practicing or playing the game.
beyond that it's really hard to give anything more than blanket advice. i've helped show some people how to hit, but everyone has different body types and comfort zones, and i kinda have to take people aside and show them how to do it based on how they feel most comfortable. the same goes with fielding, particularly in light of the fact that all positions should be approached somewhat differently.
oh yeah, PRACTICE. no matter what kind of advice you could ever get in baseball, 90% of the act of getting good at baseball/softball is getting familiar enough with those techniques and body movements that you don't even have to think about them as you're playing. really, the best thing you could possibly do is find someone nice that is willing to take you aside and help you get better. i would imagine someone from your team would be interested in doing this, unless they suck at baseball or are dicks. i am not that great at baseball, but i know enough about it to help people get a handle on how to do things. that said, i really like it when someone asks me for some help or some advice on how to get better at the way they do things.
i dunno this is shitty advice maybe i will post here again when i think of something better