Welcome back!
In DDO it's easiest to focus around one stat as much as possible. The fancy enhancement trees allow you to get a casting stat to-hit & damage (Harper: Int, Falconry:Wis, and Feydark:Cha) which is why they're usually quite important to gishy builds (like a Cleric where you can use Falconry and play as a Wis-max build). To play a caster you functionally need a stat maxed, otherwise you'll at best be dealing half-damage with no option for CC effects.
Outside those enhancement trees, the F2P option available to a shifter: Bard Swashbuckler (Int or Cha to-damage) plus Wizard or Sorcerer EK (Int or Cha to-hit, respectively). Swashbuckling stuffs you into SWF anyway, but at least it comes with nice crit bonuses etc and SWF works fairly well with EK. Some sort of /x3 Bard seems fine for that? Sorc can't self-heal though.
The biggest problem is there's no good synergy with Shifter then. If you just want the RPL that's fine, but otherwise your stat bonuses are off (Wis mainly) and you can't even rage without spending 11+ AP into your racial tree. Also -2 Int sorta hurts for Wizzy mix (although it's not a deal-breaker). Also, Howl of Terror is Wis-based.
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TL;DR: you could go Int-based Wizard 17/Bard 3 using Pale Master for self-heals (main = EK w/some Swashbuckler) and just ignoring Shifter tree while casting Wizzy spells, or you're going to have a bunch of anti-synergy in your build. Or Bard/Sorc 3 using SB as your main tree, as a Cha-max using Bard casting.
With access to more classes it gets a lot easier. What classes do you have? You mention FvS, Warlock, and Druid which are all P2P but also say you don't have paid stuff. The above assumes you're F2P entirely.
If you have FvS, just going FvS 20 seems solid. You can then run Wis-max using Shifter stuff (FvS gives Wis-to-Hit-and-damage), War Soul for a DPS tree + Trance, and cast/melee just fine lol. Run THF and call it a day. Obviously tons of heals as a FvS, and you can use Howl of Terror SLA for funsies
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So, what do you have access to and what seems interesting?