Install the tirgger/sear/disconnect/leaf spring to hold things together, slide the mainspring housing into place and pin it hold all together, DO NOT INSTALL GRIP SAFETY AT THIS TIME. Pull the hammer back to the "full cock" position, and fit the thumb safety first, as you can see inside where the "nub" rolls up behind to block sear movement. Then remove the parts and leave the trigger in frame. Fit the tail length to block the trigger bow from moving unless the grip safety is held to tilt the tail down from behind the trigger bow. I have my 38 Super race gun "pinned" so the grip safety is held as if pistol was gripped at all times.
Try not to let the hammer drop to half-cock, as it will damage the sear over time if allowed to do this. DO NOT drop the slide on an empty chamber either, manually ease it down, will supposedly damage the sear/hammer surface also, don't know if true, but I do not do this, as I see others cringe and have a fit if a novice does this when looking at a 1911 or do it to their own not knowing any better.