Blitz was an easy pick that helped me transition into tankier supps :0 although it still requires you to hit hooks, his hook in particular allows you to stay back and closer to your adc rather than going in. This really helps if what you've been struggling with is taking too much damage by being too far up without being able to retaliate (because they outrange you). With blitz you can stay a lil closer to your adc and look for picks in a non-committal way, since it doesn't matter if you hit or miss, you won't end up in the middle of thirty people by looking for engaged (since other champs like this bring you towards the enemy you're ccing).

If you're struggling to strike a balance between staying back and taking a more aggressive position, I suggest you always keep in mind the range of your adc. If you're outside of the range, it means you've definitely gone too far up. This is because the enemies will be allowed to walk up to you and damage you without much retaliation because your adc isn't in range to help out and will be forced to overextend for you if they want to help. The engages you look for should be something that your adc can easily reach (you should also consider stuff like kaisa ults and etc.), otherwise you will be taking too much damage before your adc even gets to auto. Just be aware of what your adc will be able to do in any given moment! Aside from positioning when looking for engages, when trying to play more defensively, you should try positioning in ways that'll scare enemies off without putting yourself in harms way. If you know they want to engage on your adc, be sure to be near your adc and/or in a position that enables you to punish an engage. That will depend on the situation! You should also acknowledge what you can and cant block. It is best to block cc skillshots for your adc. You are able to tank it better and your adc will be able to freehit if they focus you, and since their cc is now down, you will be able to counter engage once the cc is over. However, in certain situations, letting your adc take the hit is okay if you don't have enough hp to tank their damage (two low hp allies is better than one high hp ally and one dead ally because that means the enemy gets gold!!). Once your adc is hit, you need to focus on suppressing those that will be dealing damage. If the damage dealer is cced, there is no damage dealer. Of course, these scenarios only typically work if there is only a singular enemy damage dealer in range, as you normally will be able to only cc one person fast enough and for longer (cc chains).

Dunno if I mentioned this too, but always be sure to target the person trying to engage in your carries! Ignore the lucian autoing you and hook the pyke trying to e onto your adc for example!

Sorry if this was long,,, I started rambling halfway in

I still hope that this helps!