So, I have Gloomstalker Ranger that soon (I hope) will hit lvl 6 and I thought that MC'ing into Cleric would be a nice addition seeing as Rangers barely get anything at lvl 6  besides HP. I considered Druid but think Cleric gives me the most to round out stuff. I specifically want the cantrip Control Flames(for lighting purposes, gotta get that advantage when possible), which Druids and Wizards can get and also Arcana Clerics as they get 2 Wizard cantrips. I also want some more spell versatility as Rangers have some real weak spell selection as it is not prepared but very few known spells. My character is primarily an archer with sharpshooter and archery fighting style but sometimes is called upon to do some healing or other stuff so either Cleric or Druid is fine really I guess. My Ranger has 18 DEX and 16 WIS so spellcasting is alright imo. I have spoken to my DM about going as an Arcan Cleric and got the OK.

As an Arcana Cleric you get 3 Cleric cantrips and another 2 from the Wizard list along with 4 prepared spells at lvl 1. I was thinking Sacred Flame(for something that needs a save when I can't or shouldn't straigth up attack something), Spare the Dying(because really what else?), Thaumaturgy in addition to Control Flames and Gust(naturry shenannigans?) from the Wizard list. 

For the spells I thought I would just prepare these and not really change them until something specific turned up. Cure Wounds, Purify Food and Water, Detect Poison and Disease and Create or Destroy Water. Arcana Clerics always have prepared Detect Magic and Magic missiles. I thought these give me some nice, flavourful out-of-combat utility as Clerics are ritual casters and these spells generally don't need a material component which I thought was fitting, although I do have a component pouch if I need it. 

My cahracter knows Healing Spirit already but it really isn't that easy to use in combat so I suspect that Cure Wounds will be nice to have.

So, any suggestions about how to do things differently either by spell/cantrip selection or even MC'ing into something different to achieve my goals are welcomed :)

Just a few comments, druids also get Control Flames and Druidcraft cantrip which both do what you want regarding torches.

That said, in my experience Healing word is the best healing spell in the game until heal comes about, since the rules only require 1 hp to get up from unconcious and healing 15 hm doesnt do much anyway (cure light wounds). With Healing word you can return someone as a bonus action and do something with your main - even more important when you are primarily an archer since you can then use your action to fire some arrows and then get someone up from unconccious.

As a cleric you likely also want Guidance, arguably the best cantrip there is. Give +1d4 to all out-of-combat skills.

I would also considder Bless for a first level spell. Really good concentration that stays relevant forever. Giving bonus to hit and saves is everything you want. 

Hmm, yeah. Going Druid does give me Control Flames and nature flavour with Druidcraft, it's just that that's all, only 2 cantrips while an Arcana Cleric gets 5. Since I don't plan on doing more levels other than Ranger after this it's enticing to get as much as possible that stays relevant for a long time. I feel like if I go Druid I should at least go 2 levels deep in order to get Wild Shape, not for combat but for utility maybe some easy hit points buffer if necessary. Druid does give more nature flavour with ritual spells though so I guess I really have to think this over. I also haven't picked Absorb Elements yet and going Druid gives me the option to prepare it and take the few cool Ranger specific spells there are later.

I multiclassed into Forge Cleric (currently Gloom Stalker 5/Forge 2) and it's been a delightfully complementary mix.

My ranger has a similar build to yours (primarily an archer, Dex 18, Wis 16, no Cure Wounds) and functions as DPS/party healer. I chose Forge because the domain spells were focused on martial buffs and utility (Identify and Searing Smite always prepared, domain feature giving +1 to AC or attack rolls/damage, etc.). As for you, it really depends on how you want your character to play both mechanically and in RP. A ranger delving into druidic magic is pretty seamless, but a come-to-WeeJas moment that turns you into a cleric is also super fun. 

For cantrips, you'll regret not taking Guidance. It's useful for anything. You also might consider taking Light instead of Control Flames. Control Flames is useless unless a torch is already lit, whereas you can cast Light on anything you touch - including an arrow you then shoot into a dark cave. 

I wouldn't bother with Cure Wounds, especially if you have Healing Spirit. Take Healing Word instead. If a wyvern takes down your barbarian, the difference between a Cure Wounds d8 and a Healing Word d4 isn't significant when the wyvern attacks on its next turn. At ranger 5/cleric 1, you'll be able to bonus action cast a level 2 Healing Word to get the barbarian conscious and still get to shoot a couple arrows at said wyvern using your action. If you take Cure Wounds, you lose your ability to attack, and you don't do all that much more healing. 

I second taking Bless and also recommend its offensive counterpart, Bane. Finally, I vouch for Protection from Evil and Good. Gives disadvantage to any fey/undead/etc. attacking you, makes you immune to those creatures trying to charm/frighten/possess you, and gives you advantage on saves if you already are frightened/charmed.

Best wishes with your multiclass! 

Thanks, theologyofbagels, I never thought of a Forge Cleric MC. The lvl 1 feature that could grant me a magical +1 longbow would almost make it worth it in itself. You're completely right about Cure Wounds vs Healing Word, HW is much more useful. I do really rather want Control Flames more than any thing else though as it would both allow me to snuff out any campfires or lanterns any enemys might have and also allow my non-darkvision party members to have a smaller but still functional radius of light from 1 or 2 torches and allow me to take a step back into darkness to take advantage of the possible advantages I might get on attack rolls while not completely running away from my party. As it is now with 3 non-darkvision people in our party it's not very often I get to go somewhere in darkness and actually use the "invisibility" I get from the Umbral Sight feature. So far it's only been 2 times and only really 1 of those where I went alone and demolished 3 yetis on 2 turns..... If I really need to use that lighting arrow trick we already have a Cleric with the Light cantrip that can use it on an arrow. I've been leaning more towards Druid lately though as they have more spells that feels in line with my PC like Fairie Fire and Charm Person and also has a lot of the 1st level spells a Ranger would never take for himself due to limited known spells but would actually really have the ability to use sometimes like Jump and Longstrider, Absorb Elements is also a good lvl 1 spell that stays relevant for a long time, arguably more so the higher we go in levels. I know you don't really get a lot at 1st level Druid but going another lvl gets Wild Shape that could be cool and potentially a decent hp buffer if needs be. Also some nice features like the Shepherd spirit totem.

I highly suggest looking at twilight clerics, you get unlimited dark vision and the ability to give all party members dark vision for 10 min. Party gets ambushed at night now all can see. You said 3 members don't have ability to see at night. How much of a game changer is that?

Haven't even looked at Twilight Cleric. It seems really nice in conjunction with teammates that's for sure. Gonna have to talk with my DM on that one but I'm still more enclined towards Druid atm.

Multi-classing into a Twilight Cleric is also a viable option. The Twilight features mesh REALLY well with the Gloomstalker features I think. Just food for thought.

There are so many good dips you could take into Cleric. I'd suggest planning ahead as to how many levels you actually plan to take while multi-classing. 

For me, I'm only taking one dip into the Knowledge domain. I took expertise in Arcana and Nature (expertise is so good even with -1 in intel) and got 2 more languages, making me speak quite a number of them. I also like both of the prepared spells in Command and Identify. 

I chose Guidance because you can use it on yourself as well, word of radiance for AoE option, and Thaumaturgy. You could theoretically change the colors of all flames to pitch black for a minute having the same effect you're looking for in control flames. (That's what I'm doing)

Lastly, don't sweat too much on the lvl 1s, because you need to remember you already "know" all of them. You just have to prepare different ones in the mornings after long rests.