I have spent relatively little time in bands, and when I was, I only added vocals to songs they'd already written, so... But I have a fair amount of experience writing songs on my own.
What you've described sounds like a really ineffective way of going about things. There is no overriding purpose to the songs, and things are just cobbled together along the way, or so it sounds. Unless you really don't think the lyrics are important to you, I think it's crazy to write in such a part-by-part fashion. You need some unity, and you need to alternate between the forest and the trees.
I would suggest, for one, TALKING extensively about what kind of music you want to make -- what role particular instruments will play, etc. To be fair, I've never successfully done this, but I don't think I'd even try writing music with people who couldn't do this.
And... I don't know -- you're missing a lot of subtlety by writing in such a cobbled way, I suspect... The suggestion of using guitar pro makes a LOT of sense to me, but of course people wrote great music before guitar pro, and plenty of people just don't want to bother with the program at all. But you need some way of having the song in front of you, such as on paper, so that you can say, ah this part needs to be beefed up, this transition is garbage, this vocal note should be sustained longer, these harmonies need tweaking... Without the details all basically before you, you can only really write in a crass way -- which is fine for punk, but power metal rewards greater care.
Those are some good tips, thanks.
Our lead guitarist doesn't want to use Guitar Pro because he think it's for noobs. Another of our guitarrists is kinda dumb and can't difference between a riff and a scale...
Now we are taking a thrash/heavy style, also, our guitarist doesn't care about solos or tabs, he just write the chords in a paper, he doesn't write the tabs for the song, nor for the solo, for nothing actually. I think he should change, because if something happens and we lose the paper with the chords or something, he may forget the song, and that would mean starting all over again.
People who have opinions like that are often very resistant to change, but... While I admit that Guitar Pro is kind of an easy way out, I think that keeping some kind of record of how things are supposed to be played is essential, unless you just want to be a kind of "jam band". This can be trading little demo recordings, or writing things out on traditional staff notation (which you can also do in GP).
It's a little out of my depth, but in my experience, talking about "chords" in metal is not always that informative. If you're just doing very simple riffs, chugging this power chord then that one, fine -- but for many, many interesting things, a "chord" is almost a fiction forced onto a riff, and one that hides a lot of information about what is actually going on. (Like, while the riff may all play around in the key of E minor, even starting on E, it might include the 4th, 5th, 6th, and 7th -- but if the bassist just sees "E minor" or something more complicated, he won't know where the notes fall, so if he tries to play anything but an E note, he might create unintended dissonance. Yes, this could in theory be fixed by practicing together a lot until you know just when and how everything is happening -- but why? It just seems grossly inefficient, and creativity is very likely to be limited by the pressure of having to figure out your part while the guitarist is there to play the riff for you. Personally, I often like to play the same riff over and over for days until I figure out what harmony etc. I want.)
And standard notation surely didn't come from "noobs". Jamming was probably largely popularized by "noobs" who couldn't read standard notation. But again, I understand if it's hopeless to try to convince the guitarist.
And again, yeah, I repeat the above comment on having a conversation about how the different instruments should relate to one another. Seems super important to me, and I feel absolutely blind without that kind of direction.