First of all I'll start off by saying your vocals are not going to sound like Drake. You're not that good and your wallet is not that fat. Soundproofing can cost upwards of 5 bills ($500) for a complete kit, which is some BS for pieces of foam. With that being said, I'll breakdown a handful of tips to soundproof your room on a budget.
Never trust your headphones to give you the best sounding music on the first go. Something that sounds good with headphones, sounds like mush on mac speakers. Something that sounds good on Mac speakers sounds like poop on iPhone headphones. Can I find a good medium?