Support is great, most people tend to stay away from it in solo since it requires you have good teammates to start with.
Even so, i still find support to be worth it since it can really bring yo
Generally when you play a support role, you're always behind your teams back making sure they can fully focus on pushing on and possibly even help them with that.
E.G. especially in turf, ink what they don't to increase points/special/mobilty, also ink walls as they really give a tactical edge.
If a enemy slips by and tries to take over your turf, splat them using your mobilty in your favor or AT LEAST warn your team of the intruder(s).
There's no shame in doing so, especially if half a time or even more are trying to take over as by then, Your teammates can afford retreating since Half the enemy team is on the other side of the map.
Also, everything better then your support being splatted.
Then you can help your teams pushing on, best done by ranged weapons as you can ink paths/territories in advance and overall break the enemy's team formation and if the opening arrives, splat someone yourself.
Though short range weapons can still possible aid to this with subs and specials.
Short-range weapons will mostly focus on protecting ground, though a well throw/placed sub/special does wonders.
Though in all cases, protecting your ground is still the most important, be prepared to 'switch' accordingly to ensure the best results.
miscellaneous tips:
-As support, you are going to use specials a lot.
Make them count, especially if your using a short range weapon.
-short range weapons mostly focus on protecting, long-range weapons have a bigger additional focus on directly helping your team push.
Personally, i've been using the dual sqeulchers (REALLY good support weapon) and heavy splatling as long range support.
And the slosher and carbon roller as short range support.
Alot of other weapons can play a support role though.
All of your preferred weapons can play support effectively too!
I also wrote a guide on support play that may help.
(don't expect too much from it though)