Hi, I recently started using a rogue multiclass into a level in fighter and I need help working out what would be the best tactics to use its abilities. Any and all help maximizing the use of this character's abilities will be appreciated.

Can you share some more details? What level of Rogue are you? What subclass? Do you want to level fighter high enough to get to a subclass or just one level for proficiencies? I'll try to give some generic advice...

Right at level one the big decision you want to make is the fighting style you'll take. The important thing here is that you're going to want to focus on a fighting style that helps you with your sneak attack, so it has to be something that combines well with a finesse or ranged weapon. The simplest Fighting Style to take is probably Archery... this just gives you a flat +2 to your attack rolls with any ranged weapon, which substantially increases your chance to hit. The Dueling, Thrown Weapon, and Two Weapon fighting styles all increase your damage rolls, but it's relatively minor compared to what your sneak attack adds to your damage.

You can still only land a sneak attack once per round, no matter how many attacks you get, but Action Surge is still useful making sure you land an attack on your turn if you really need it. There's so much you can do already in your turn with your Cunning Action as a rogue, so you won't need the action surge too often, but you can do some crazy stuff for it. For example, you could take your full movement, dash as an action, dash again as a bonus action, then action surge to dash again and move 120 feet in a single round, which won't be useful often but it might solve some major problem you might encounter in some very specific battles.

There's a lot of fighter subclasses that have cool or interesting synergy with a rogue multiclass, but I think staying with the simplest suggestion I think Samurai would work well with Rogue, since the Subclass can grant you advantage at-will a limited number of times per day, so in those situations where you don't have an ally near an important target and don't have the ability to hide to get advantage for yourself you can still force a sneak attack against an enemy.

To answer some of your questions, my character is a level 5 rogue whose subclass is Phantom because of the hunted house base theme my DM is going with. As for what I plan to do with the levels for fighter I was thinking of taking it far enough to at the very least get a subclass; in this situation, I am thinking of either going with Battel Master (Battel field control and helping the party with specific interactions) or Echo Knight (Its manifestation ability and the possible teleportation it could give my character). On a side note, the character is a lightfoot Halfling so that might factor into how it might play.

Story-wise my character has been playing more of a defensive/ambush style with some Adamant daggers he managed to steal from an enemy cult and a standard short bow with some Walloping arrows the group Artificer made for them. As of this moment, I want to aim this character's combat abilities toward dealing consistent stealth burst damage with the possibility of also causing nearby enemies to suffer a status effect or disadvantage and maybe doing some damage to them as well.

Beyond that thank you for these general tactics they will be of use in the next session with my group.

Okay, that gives me a better idea of what you're going for.

I think it makes sense to prioritize your short bow over your daggers... adamantine weapons don't help in direct combat against creatures any more than a regular weapon, but the walloping arrows give you some great battlefield control options. As a halfling, you're slower than most enemies will be, which isn't as much of a problem when you rely on ranged attacks primarily. Although Echo Knight seems more fun in many ways and has great flavor that pairs well with Phantom Rogue, Battlemaster feels like it would feed better into your concept of a character focused on sneak attack burst damage. Most Battlemaster Maneuvers apply simply to "weapon attacks", so they can be combined with ranged weapons just as easily as melee weapons. You also choose to use most of your maneuvers when the attack hits, not when you make the attack roll, so you can be sure you're not wasting your superiority die.

A fun combo you can pull off as a Battlemaster/Rogue is using Goading Attack in order to force an enemy to have disadvantage on any target other than you... then use the hide action so you can't be targeted by them anyway, essentially just dropping disadvantage on an enemy for a round. I'd also recommend Precision Attack, which you can use to make sure you land a hit if you really want to make sure your sneak attack lands. Depending on your build I think the other two maneuvers I would recommend are Feinting Attack... a bonus action to give yourself advantage to help you guarantee a sneak attack and which adds damage to that attack... or Maneuvering Attack which is great for both adding damage and helping your allies... either allowing a squishy character to safely move out of range of a dangerous enemy, or getting an ally who's struggling to catch up with an important target the opportunity to move closer to their quarry.

Not that I want to say you should absolutely take Battlemaster over Echo Knight, but just keep in mind that as a Rogue you rely pretty heavily on your Bonus Action each round for tactical decisions, and Echo Knight is also pretty Bonus Action Heavy in its features. I think Echo Knight, interestingly enough, might actually be more useful out of combat, since it gives you a reliable short-range teleport and opens you up to a lot of potential trickery and deception.

These are a lot of good ideas. I will be using some of these tactics during my group's next session.

Another fun interaction, if you are into the investment, is to take the Brace maneuver and use a whip. The whip extends your range letting you get another method for sneak attack which is your primary damage dealer over weapon. If you pick up the Sentinel feat, you have the ability to stop them dead in their tracks and they never get to reach you. You are sacrificing a couple points of damage for a ton of control.

I will admit that a rogue can become bloated/benefit from a lot of options on each of their action types (bonus action, reaction, standard action).

Please say more. I love hearing these kinds of ideas when it comes to the development of my character's abilities.

Wails from the Grave is a nice damage spreader coupled with range because the effect is 30' from the target. The mobility of a lightfoot moving freely through occupied spaces for repositioning is very fun and useful. Picking up a maneuvers like Brace and Riposte can let you get more sneak attacks in a turn while Goading or Menacing can help by making it more difficult for opponents to harm your allies.

Your weapons of choice sets you up for two weapon fighting which gives you a second chance to hit in melee to deliver that sneak damage. I find that hitting enemies once you hit tier 2+ becomes less of a concern over losing HP from getting too close. I have found the whip and shield serves my style way better. Adding Sentinel with whip means you can maneuver around the battle field into a position which allows you to set your target up for an AoO. You could bounce a heck of a lot of attacks in a round to trigger your sneak which triggers your WftG on top of it all clearing out enemies that are already about to drop.

I would definitely want Goading or Menacing given how nuts the other members of my group tend to be.

No one has mentioned disarming strike maneuver.  I really like disarming enemies and taking thier stuff. Not to mention getting grappling enemies to drop allies without wasting damage or actions.

There is some cheazy way to use action surge to allow one action to ready an attack and it triggers on someone else's turn  for more sneak attacks. Check with your dm first even though it's raw.

I love these ideas. Please keep them coming.

For anyone that might want to know here are the current main stats of my PC:

Strength: 14

Dexterity: 17

Constitution: 13

Intelligence: 10

Wisdom: 12

Charisma: 11

Echo Knight with Phantom Rogue seems too cool not to use.

The echo knight duplicate could be reflavored as a ghost.

I was thinking of something similar when I posted this question.

I usually wouldn't allow echo knights at table I run, but I would make an exception if a player floated this kinda concept.

Battlemaster master seems more powerful, but Echo Knight sounds more fun, and not something you would get a chance to play often.