Hi Cai,
Southeast is wood,correct and SE likes water elements very much

For this year,5 yellow is there is said to be the best to have some metal elements to destroys/excaust earthly 5 .
Dont place red (i have to say that I have red wallpaper there and I dont feel anything bad except ,money cannot stay in house,lol)
You can place salt water cure this year on SE..
See where is yearly or monthly 8 and there you can place red symbols
Good luck!!