One of the easiest ways to increase the sound from your cabs is placement. You can't always put your cabs in the same place, in the same way for every room.
Each room you play in will impart it's own sonic demands. Where you position your cab(s) and how you position them makes all the difference in the world. Too often bass players will set up their gear in the same place, in the same way in every room (either out of habit or for the look onstage). The typical placement of next to the drummer and where you generally stand...same place, same way, every gig no matter what the room demands.
Some rooms I put my cabs up higher, some places lower. Some places I hear myself better if my cabs are way back against a wall far away from me, and some places they are right next to me and tilted up. Sometimes it's best to put them in a corner or next to a wall, some places further away, or angled in a way that by looks alone you wouldn't think sounds best. Experiment with it. I have two 115's and my bottom cab has wheels on it. I move it all over the place during sound check until I find the perfect placement. Though sometimes my top cab will just sit on the floor, or on another crate or something, not even that close to my other cab (sometimes "vertical alignment" doesn't cut it, though usually it does), positioned in some way where it's not riding on my bottom cab. I don't care what it looks like, I only care that my sound is perfect for me. Let the PA handle the rest of the room.
Play around during your soundcheck with cab placement. Since I started experimenting on cab placement, ALL of my problems in hearing myself have gone away. +1 on boosting the mids. What sounds good to you at home ain't going to cut it playing live. But cab placement is EVERYTHING when you want to hear yourself clearly.
