Filling up the full length of the tape

If you want to avoid the tape finish before the song ends, and also want to minimize the blank space at the end of each side, you may calculate the total duration of the songs, so you can build a song list that fits exactly the real length of the side.
Be aware that tapes usually have around two minutes more that announced on every side. In example: a 60 minutes TDK tape usually have 32 minutes in each side.

Let’s say you have this song list and you want to record it in a 60-minute TDK SA tape, like my Pure music & photography playlist:

Spotify song list

First thing is to know the exact duration of the tape. There are two methods to measure it:

1. If you have a good deck with real-time counter, it’s easy*: just do a full wind from the beginning and you will have it in the screen. Note that if your deck doesn't have a quartz locked mechanism, the time reading could not be precise enough.
2. If it’s not your case, you will have to use a clockwatch to measure it. Yes, it’s a bit boring but you will have to do it just once (if you have many tapes of that particular one, which is always a good practice). Here's a good tip: when you start the clockwatch, start also a timer for 29' (you can use the Watch app from your smartphone) so you get notified when there's only 1-2 minutes left to the end.

* The calculus will only be valid if your deck has a quartz locked motor, otherwise the counter can be faster or slower than real time measuring

A real example: this Maxell XL-II lasts for 32' 21".
Substract 6" twice from the beginning and the end and you'll get it: 32' 09".

Now start calculating the duration and adding each one, until you reach the real duration of each side. In this case I’ll show how to fit them in a 32 minute tape, so I start adding until I reach the 9th song.

As far as I know, there's no software to easily calculate that, so I use my old HP48GX calculator that I still have since I was in the university, as it lets me easily do this kind of calculation. Want to know how to easily calculate it? Watch this video and you'll find out:

How to easily calculate the total duration of a playlist with an HP48GX.

Don't have a real HP48GX? No problem, you can install the free emulator to use it in your computer. If you don’t have it (yes, it’s highly probable, I know), you can just download a free emulator from HPCalc website. The Emu48 that I also use is available here (windows) and here (Mac). You will also need to download the ROM file and load it into the emulator to run it.

See how in this video:

Clean heads, capstan and rollers

Although is something that should be considered basic and easy to do, most people didn’t do usually… and the majority never did. But for a proper performance you should clean them every 10 hours of playing (well, or anytime you need it, i.e.: after playing an old dirty tape). Use a cottom swab and good alcohol (preferably isopropylic than 95% one, commonly found at home, as the former doesn’t leave any residue) and follow the instruction of your deck’s user manual.

Take the deck to service

If you want your recordings to have very good quality and you want to keep enjoying them for many years, I strongly suggest you to consider taking your deck to a professional technician. Please, you read carefully this: if you are serious about doing excellent quality recordings, forget doing yourself. You better take it to a real, professionally skilled technician. There’s a difference between aficionados and good professionals, and if you really want your deck to perform at its best, stop doing yourself and take it to a real excellent one.
Although not common, there are still many qualified technicians out there. You just have to look for an old TV and radio repairman. You can find some in the Internet but sadly many of them aren't in the net; you can always search by the old way: asking people, etc...

GSP Iberica’s excellent service

If you need a good technician in Europe, I can suggest you Sergi from GSP Iberica at Barcelona. He’s an expert vintage HI-FI technician with 30 years of experience with decks and reel to reel. He has repaired many of my stuff and I’m so happy with him. He’s very neat, picky and has a wide knowledge of what he does. Check, in example, what he did to my superb Pioneer RT-909 reel to reel. He learnt with AKAI’s engineers in Japan factory many years ago. If you're looking for someone to repair your walkman in Europe, especially if it's a SONY DD, consider contacting Marian Mihok at Slovakia.
If you are looking for someone in America or other places, contact Pacific Stereo or try searching at Tapeheads.net (look at the bottom of the page).