We are in CA, south of SF Bay. The following is a general desc. of what we did.

Download manufacturer's installation manual. Went through it and learned it as though we were the installers.

Looked at our old windows, inspected them as though we were doing the work. Where were the gaps? mildew if any? window trims interior and exterior that would need reinstallation or replacement? where were the problem corners that were not square? stucco refinishing?

We needed new openings, so we researched both online and by talking to a local carpentry/wood shop how that was normally done. They were helpful telling us how they would cut the drywall, cut the stucco outside, support the frames, needing a giant header etc. We forced ourselves to mentally walked through the details step by step as though we were to do it ourselves.

We also learned how to install our own French doors on our particular floor like we had to do it ourselves. It included identifying what framing around the opening we wanted to replace because we did not feel it was sturdy enough, how we would seal it properly, what to do about known level problems, etc.

When all was done, we were as well educated about the process as we could be. We had identified what seemed to be obvious simple straight replacement holes. We had identified window openings with problems. We also knew which windows needed trim work and stucco finishing, where the new openings were and a good idea of what was involved and how to install the doors properly *IF* we were to do the job ourselves.

We listed any questions we had. There were still holes in our knowledge because we are still just amateurs homeowners. No amount of paper-study can replace work experience.

We listed a secret list of "test" specifically on those problem areas we had identified. A competent contractor should be as picky as we were or more so. If one came out and did not notice those areas, we could drop hints from that "test" but never came out to point anything. We wanted to see if he/she could notice the same problems.

We asked for the contractor to tell us right there what he/she thought must be done to each opening, especially the more involved openings like ones requiring trim work, rot repairs and the new openings.

We acted semi-dumb but asked pointed questions. We wanted all our questions answered clearly, honestly and patiently and would not tolerate the typical CA Bay Area contractor homeowners-are-dumb attitude.

From all that, we graded each contractor.

The one that got the job was the one who came out, identified every single thing on our list without us saying anything! He even pointed out areas we did not notice. We paid him what he asked and never regretted it.

I sincerely hope this helps and you find a darn good contractor for your job.