Some things that can help a lot:
1. Corrective exercises (like mckenzie press ups, etc.)
2. Keeping good posture during everyday activity ... This includes sitting. You can help this by putting something like a rolled up towel between your back and the chair while you're seated, as this helps you sit up straight for longer periods of time. <- useful for office workers, etc.
3. Learning to brace your core. If you have to pick something up, your best chance of doing it painlessly is by bracing your core, and this is also an important injury prevention thing. You MUST do this during lifts like deadlifts when you're at the gym as well. Very important.
I currently have slight acute lower back pain due to an accident at the gym, and I'm focusing on those three things above, which is working out very well. Also, REST is important, don't stress your back further if it's already hurting you. Seeing a physio is also important, as it is more personal and can often give you a better result than sites like youtube, etc.