Most squeaky floors are caused by the sub-floor (plywood under finished flooring) not being screwed and glued to the floor framing. Sometimes glue may have been used, but dried out over many years. The only way to fix that is to remove the finished flooring and add screws in the sub-floor in the squeaky areas. If that doesn't work, you may need to remove the sub-floor in that area and replace it. Be sure to use both glue and screws when installing the new sub-floor. If you have an unfinished ceiling below the floor (like a basement), you may be able to add blocks between the joists with glue on top and toe nail or screw into the subfloor from below.
Loose or Cracked Grout in Tile Floor
If your tile floor grout has started to crack or come loose, you will need to remove the grout and re-grout or caulk. The best way to remove grout is using an oscillating saw with a grout removal blade installed. Once you have removed the old grout, you can re-grout the tile. If it's a very small area, you can just remove the loose grout and use caulk to repair. Sanded and non-sanded caulks are available that match many common grout colors. After installing new grout, be sure to seal with a grout sealer.
Gaps between trim and walls
You may notice some areas where there are gaps between your trim (baseboards, window/door casing, etc.) and your walls or gaps where sections of trim meet. Most homes, even newer ones, have walls that are not perfectly straight and my cause gaps with the trim. It is standard procedure to caulk the outside and top edges of all trim where it meets the wall, as well as all seams between pieces of trim. If you see gaps, caulk those areas, allow to dry, and paint. See our Pro Tip Section about how to get great caulk joints.