I did my first gig this year after 23yrs without and about 13 without playing and it was great to get back into it (other than the late nights). For me, what I noticed is that:
1 - its still about the people you are playing with. Liked the guys from my college band; like the folks I play with now. Been asked to sit in with people with less than optimal attitudes, and I don't need to do that, which is good.
2 - The tech for making song/lead charts is really nice. I did a fill-in gig and had to pick up 25 songs in about 2 weeks, so I used Finale Songwriter to make some charts for me. Very helpful to have either printed for reference pre-song or on an iPad with a clip for a mic stand.
3 - don't think any pedals are must have, but I have a TC BH550 head and use the tone print function for some grit and a light overdrive as well as EQ. Works well. I have an always on compressor for a 4:1 reduction to use primarily as a limiter and like what it does. I just started using a TC mini Flashback delay as a reverb to thicken the sound with a group where we have up to 3 guitarists, so perhaps consider something like that if your sound needs to be thickened up. I also have a chorus pedal for certain songs, but not sure I will keep it.
4 - the BH550 has an on-board tuner, so I'm covered there. The Snark clip on tuner is becoming ubiquitous, but I think they look a little too beginner-band for my taste in a live setting. I have one for when I'm not using my amp head and use it off stage for my back up bass, then put it down on the amp. If I need to tune more than in between sets, something is very wrong. My backup bass is currently tuned to open C for a specific song, so I use my backup to deal with any alternate tunings. I think the pedal tuners with a mute switch are really nice and much more professional looking and sounding (the TC Polytune mini is very popular and the same technology they use in their amps; it is very nice). I like the mute button as well, so that the audience does not hear all the twanging during tuning, as well as the mute is great if you need to switch guitars or unplug. Pretty fair price and can be also found used on Reverb or (sl)E-(azy)Bay.
5 - don't know your amp, but even with mine, I find a good set up check and sound check works well. I set my amp EQ, then adjust my tone knob and pickup balance for a given song to get the tone I want. Works well so far.
6 - ear protection. Tinnitus sucks, so consider good custom ear plugs with a reasonable filter or IEM's to protect your hearing. Your ears are degenerative; protect and treat them that way! I have 1964Ears quads and even for a 3-piece in a small setting, they were helpful because I had to stand right next to the drums on a postage stamp stage. My ears felt great after. Even if you have balanced and reasonable noise levels, consider this. They are really helpful for protection and monitoring. Couldn't believe how helpful they were and a great investment.
7 - personal recording devices - I use an iRig and will often record my parts for cover songs, just to get a better sense of my timing and tone. Couldn't do that so well back in the day without serious recording gear, but now for $100 and free software (GarageBand or Audacity), you can record and critique yourself. It also allows pitch shifting a song so that you don't have to go to an alternate tuning to practice. E.g. we play Superstition, Breaking the Girl and Would and I just set up the song in GarageBand and play over it after using the pitch-shift function to make up for the 1/2 step tuning.
I started the Berklee Bass Professional Certificate Program to get my skills up to snuff and improve further, so lessons/classes may be something else to think about. Hope this is of some help.
Have fun! I did not realize how much I missed playing and you will likely do fine given you stayed active in music.
)
