Have been digitizing taped analogue audio since windows 98. Been using tape since 1965. I have gained my knowledge through life-long experience.
Tape (in any form and if not stored under perfect conditions) has a short lifespan and quality degrades as the years roll by. The purpose of digitizing is two fold - 1) to capture a faithful copy for archive purposes, 2) to make digital copies for playing on modern equipment. Any sound-shaping work is done post-production after recording not prior.
Preparing the tape deck is very important. Clean the tape heads with tape head cleaning solution (if you can still buy it). Clean the black pinch wheel with baby shampoo - about 1 part shampoo to 3 parts warm water (why?) ordinary washing up liquid is too astringent and could soften the rubber on the wheel. Use good quality cotton buds. If the pinch wheel has not been cleaned for a long time, brown or black residue will be on the cotton bud. Keep cleaning with fresh cotton buds dipped in the solution until there is no residue. Let the wheel dry before inserting a cassette. Clean the RCA phono sockets on the back of the deck with a little bit of surgical spirit on a clean cloth. Try and use good quality connection leads rather than the cheaper bell wire types.
If you are digitizing an album, I personally would do it track by track. Find the loudest part of the track and then adjust Audacity recording volume so the peak is at -6db. Audacity’s record and play back meters are very, very accurate. Turn OFF the Dolby (or any noise reduction system) on the tape deck. You can use Audacity noise reduction post production. Try and record a few seconds of tape with no audio at -6db and use this clip as a reference for the Audacity noise reduction.
Queuing up the beginning of each cassette track is not critical. Simply click the record button in Audacity as the previous track starts to fade. Stop recording as the track fades and the next track begins. Once done, this is your raw cut and can be “Saved as” in Audacity’s own format. This forms an archive. I would advise making a WAV copy as well.
All subsequent work should be done once the open track is “Saved as” again. Simply find the millisecond the track starts and mark it. Highlight the audio before the marker and use ctrl x to snip the audio. then add “Silence” about 3 seconds is fine. Do this with the fade out. This called top’n’tailed. Once edited, Export as a WAV - this is now the master copy ready for archiving. All post production work should be done on a copy of the master.
To recap about copies: We have the original raw cut archived in Audacity’s own format and a WAV copy made from this = 2 copies. We have the edited version, top’n’tailed (with no eq) archived as a WAV master file = 1. From a copy of the master WAV all post production work is done = 1. So we have 4 copies of the track in various stages of editing.
Make a back-up of these four copies, preferably on another drive
Why make all these copies? Sure as eggs are eggs you will want to go back and tweak or adjust something. All you have to do is open the master (the one which has been edited at the start and end) or go back even further.
Try this: load the master WAV of a track (the copy that has been edited at the beginning and end with NO eq or effects) use the Loudness Normalization feature at its default setting. Export as MP3. Play on your portable device and you will find it sounds pretty darn good. Why? Because the Loudness Normalization reduces the volume (loudness), and on playback on a portable device there is a lot of headroom for the players EQ or Megga Bass, and will not distort the devices outputs - even at full volume.
Remember taped analogue recordings will deteriorate. Thus the importance of archiving a faithful copy of the original cassette recording.
Hope this is useful