Some more explaination about what you're having problems with specifically would help us give you advice in that area, such as one particular song or style that's giving you grief.
If synchronizing or 'locking in' isn't happening too well, try paying closer attention to your other band mates, and them to you, with your eyes, ears and mind. And practice. And practice. And practice.
haha, good advice! you might need a few pulleys though!, jokes.
Maybe all try playing to a metronome? That can be a difficult approach though if your are not together in the first place. Maybe try having a few sessions just with the bass player, because the drummer and bassist are the engine room! If you two have it together, it should be easy for the rest of the band to follow along
A more vague question I haven't heard. You paint a mental picture of 4 guys playing different things, with no sense of what anybody else is doing. I'm sure it can't be that bad, but we need more info, a vid or recording would really help us help you. Watso you're a scream and steadily becoming my favorite poster.
"Tightness" was definitely an issue in my band. The most important thing I/we started doing was
I started playing to a metronome and understood my role as the bus driver. Keep solid time and let the other musicians fall on top of your groove.
The bass player started watching and listening for my bass drum. Especially for where "1" is. Sometimes he just wasn't real tight on the other notes he's playing with me, and the rest of us struggle as a result.
I started practicing with just my bass player. Understand that you and the bass player are the ocean in which the singer or other instrumentalists float on as the ship. The less waves, the less currents, and the more smoothness and togetherness, the easier everything else will flow when on top.
Know your parts and your changes. Listen to the music as much as you can, especially if there is some complexity to it and it's not just 8-bar phrases going from chorus to verse or a simple change in section. Know when they're coming, play fills that fit the change and are easy to play along with as another instrumentalist.
There's a lot you can do to help, but as some other people said, audio or video would help us hear where you may need strengthening.
But in just about any pop, rock, jazz, etc. band, I place so much emphasis on the rhythm section. No one will listen to the singer if you and the bass man are tripping over each other, and the guitar solos will not sound good if you can't lay the foundation for him to solo over.