I havent played with my band for a while, but recently we got back together to play some stuff for later the year. It kinda feels loose and unfocused, kinda just playing through stuff. What are some of your suggestions about how to have a good practice? What do you guys do during practice? And also, we have never made our own stuff, just because we played covers last year and thats it. But I really want to start writing our own stuff. What do you guys do when you get together with your band to write?
practice with a metronome that everyone can hear (run it through the PA if you have one so that it's loud enough).

record your practice so you can listen to the playback and determine whereyour weaknesses are.

as far as writing, i start the process on my own, coming up with riffs and piecing them together... maybe a few one-liners to give the singer somewhere to start with lyrics. then i bring what i've got to the table for the entire band to hear/make suggestions/start writing their own parts (which they do on their own time for the most part - only time NEW material is practiced at practice is in the very early stages of bouncing ideas off each other. once it's "written" it's no longer what we call "new," so we run through it at practice same as we would a cover song). each time the process is a little different, and it really depends on the material you're working with. prog, for example, requires a LOT of interraction between members in the writing stage, whereas for pop-punk the guitarist can lay down a few chords, show up to practice, and the drummer can immediately lay down a beat, so forth and so on.
When writing songs I actually have a fully formed song ready to show the band. I usually record a demo track of it and have chord sheets for everyone. "Responsibility" on my profile is a good example of where I have recorded a demo and sent it to the band. It now has lyrics and drums, but you can get a clear idea of how I'd like the song to sound.
And no, Guitar Hero will not help. Even on expert. Really.
Me and my guitarist do writing behind are computers. We fire up Guitar Pro/Fruity Loops and work out some parts for the song. We also add some concept drums and bass completely open for interpretation for their respective bandmembers.

This way we have a complete song ready for rehearsals, and we can finetune the entire thing.
Begin practice with a set list and play as if you were playing a live show, bonus if you can record yourself for later evalulation (outside of practice, or the next day). You usually know which sections are weakest, work on those together, first the section, then from the beginning. Try to add one new song a month, or more if you're really productive.

I've used a couple different approaches to song writing as a group. I find that if you plan to write a complete song yourself, try to identify the strenghts and weakness of your bandmates (and yourself). You own band is really your primary audience, so first make songs you and your bandmates will like. Write with everyone in mind.

Those times you don't have a complete song, just play the part you wrote and see what everyone comes up with to accompany that part. In those cases, I would save the arrangement for last. Really listen to what your bandmates are playing, it's your best source for more ideas (especially the "mess-ups"). Don't automatically fall in love with your own riffs, sometimes a month or two passes and that riff that seemed so perfect and important sounds stale or cliche.

You may go through writing slumps, I recall playing the same six songs for probably four months, but stick with it those things pass.

I also find that stopping in the middle of what you're doing to 'give a lesson' during practice is generally counter-productive. Finish the song/section no matter how bad it sounds, then go back to explain the part that's not sounding right. Avoid noodling while someone is talking or playing a part for the first time.
Thanks for the tips. I had another practice today (not with the whole band, just pretty much just me and the singer) It felt like it was pretty productive (practicing techniques and working out our parts for covers) But still the whole songwriting part felt like it wasnt work. Maybe im just one of the people that write on his own and share with the band later, I find it hard to be productive writing with bandmates for some reason.