1] FL STUDIO can consume a lot of ram and CPU as your projects go bigger and bigger. Make sure you have lots of ram and a good CPU, alternatively use 64 bit fl and 64 bit plugins to ensure the extra ram on your PC is being utilized.
2] Always assign each and every sample you load into the mixer FL wont do it for you, this will help keep things organised and prevents confusions later.
3] When doing chops and slices on audio files make sure to use a declicking option to prevent any clicks and pops (DC offset)
4] Load an EQ on every mixer channel and remove any unwanted frequencies, this will keep the mix clean.
5] Tools -. Macros -> Purge Unused Audio Clips
this will remove any audio clip that you may have loaded but not used in the project. Very handy to save RAM.
6] Create a Sub-mix/Buss of instruments falling under the same category. e.g: Drums, Bass, Synth, Vocal, FX. This will help you in controlling the dynamics better also will keep things organised.
7] Never over compress your sound unless you are trying to achieve a certain effect
8] Always use a good spectrum analyzer to make sure there are no unwanted frequencies specially if you don’t have a full range monitor or headphones.
9] Try removing elements instead of adding more for power, sometimes less is more and can really open up the track.
10] Get your mix right and mastering will be a cakewalk
11] Do not clip, if a plugin shows red peaks bring it down a few dB, Red may look nice but it will burn a hole in the dynamics.
Credit : Zoheb Khan