There are many resources out there discussing about recording levels. Personally I still encounter many recordings I received from other engineers or producers that were recorded either way too hot (more often) or too soft. For anyone who wants to record well and maintain a good healthy signal between the headroom and noise floor, you need to remember this:
In my opinion, the best practice will be keeping your PEAK level of the individual track to +/-3dBfs within -20dBfs in your DAW. This is especially important during recording and mixing if your approach is analog or hybrid between analog and digital signal processing.
Below is a screenshot showing how 1kHz Sine Tone at -20dBfs looks like on the VU meters. This is to express +4dBu = 0VU = -20dBfs as shown on the diagram above.