Yeah, it´s an a idea.
Thanks for spending some time to give some tips. I eq strings only to give them some brightness and presence because sometimes they sound to bassy and unclear. Yeah, automation can be very usefull in some cases but I try to do all I can when they are just midi files, change the velocities and all that shit to avoid a lot of work with automation.
I see that you use MOTU Symphonic, what are your opinion about it? I tried Miroslav Philharmonik and I didnt like. Some of the sounds like the brasses are outdated, the instruments dont have much deepness, sounds harsh even with reverbs and they dont have impact as orchestral sound. This could be a strange opinion because Miroslav have some very good reviews but I am not convinced. EWQL is not a option because I dont have a big machine to run a such heavy VST. So I might try Motu Symphonic.
Personally, I use EWQL Platinum, and occasionally Miroslav Philharmonik, and those pretty much cover everything I need. I also own MOTU Symphonic, but I never use it. It's not bad, and if it was all I had, I'd make the best of it, but I much prefer EWQL and Miroslav.
I agree about Miroslav's brass for the most part. But their strings, despite being an aging library, still sound excellent in a lot of ways. Also, their woodwinds sound great, and it has some nice percussion too.
I use about 90% EWQL and 10% Miroslav. But whatever your library of choice, if it sounds good to you, that's what counts. To help blend it with guitars, your arrangement will go a long way.
Assuming your arrangement is decent and too many instruments aren't automatically fighting for sonic space, then basic level matching should get you most of the way there.
EQing should help you make up the rest of what's left. You probably already know to high-pass and low-pass the guitars. Don't do it with the guitars solo'd. Do it with the entire mix going. Start with the high-pass. Use a good quality EQ with a solid high-pass, and start running it up the frequencies slowly until you start to hear a change. You should start hearing the low end tighten up a bit as you pull some low end out of the guitars. Once you feel like you've gone too far and the guitar get too thin, back it off a bit. If the point where it sounds right turns out to be higher than you expected, don't worry about it. In the context of the mix is what matters, not solo'd.
Then start the low-pass. Do it in a similar manner. There's a lot of fizz and junk in the highs that don't really benefit the guitars, so you can start running the low-pass down the frequencies, once again with the entire mix going, until you start to hear it working. As you do this, you should start to hear the high end of the mix breath a bit easier. Run the filter down to where it's taking too much high out, then back it off a bit to where it sounds right. Once again, don't be concerned about the number. Just trust your ears.
Assuming you like the overall guitar tone you're getting, you should be pretty close by this point with the high and low passes set. Now you can fine-tune by carving out some room in the mids. Don't overdo it because the mids are where your guitars live and if there's not enough mids, you'll be chasing the volume and throwing off your mix.
Use band filter on a parametric EQ, pretty much any DAW should have one, and set it to a somewhat narrow, but not too narrow Q and turn it up several dB, like between 6-12. Sweep slowly through the frequency range and listen for spots that sounds bad, or cheap, or boxy, or too harsh for your liking. If you find any, set the filter to that freq, and carve out a small chunk there. Use your ears to determine the Q width and how much to cut. You may or may not need to do this in a few places.
After you've done that, you should be pretty much there. If you're trying to mix guitars, is it safe to assume that you're also using bass guitar? If so, bass frequencies take up a lot of sonic space in a mix, so will probably need to do similar things to the bass guitar to get it to fit as well. Also, this is another place where your arrangement will really matter. If you're using orchestral instruments and a bass guitar, and you're having the contrabass/cellos and/or other bass orchestral instruments do one thing, and the bass guitar do another, you're having a huge nasty conflict in the low end.
Good luck, hope this was helpful.
There some things that I already know but some others could be very usefull in the future. 
