This model is for Quarterbodies only. These are the most finicky type of FE gens, and as such, they require specific settings to look good. My team is struggling to improve them, but our preferred settings are:

Use the Macross Ultimate model from this page.
DPM++ SDE at 15 Steps, 512x512, CFG 4
If you have Umi AI installed, you can use these negatives to improve the art style:

lowres, bad anatomy, bad hands, text, error, missing fingers, extra digit, fewer digits, cropped, worst quality, low quality, normal quality, jpeg artifacts, signature, watermark, username, blurry, out of focus, censorship, (multiple boys, multiple characters, multiple girls, multiple views:1.2), boobplate, NEGS Bad Artist Anime by nick-x-hacker, NEGS Bad Artist OG by nick-x-hacker, NEGS Easy Negative

And finally, this is a good starting prompt to try out:
solo focus, (quarterbody, frames, vanilla fire emblem:1.1), simple background, {caucasian|dark skin|colored skin}, {1boy, mature male|1 boy, teenage boy, aged down|1girl, mature woman, large breasts|1girl, teenage girl, aged down}, {<[military]>, <[heavy armor|heavy armor]>|<[Torso]>}, <[hair color]>, <[hair length]>

Remember to run this Lora at 0.8 strength with the Macross Ultimate model for the best results!