Search Colorful Boho for decor ideas. This article has some fun colorful ideas
I suggest bigger pieces you stick with neutral tones then add color with the smaller pieces. That way you can change add without having to rebuy the bigger items. Invest in a good couch and a good bed. This bed always reminds me of an antique crib. Good Inexpensive mattresses I would search Zinus on Amazon
Colorful throw blankets are an easy way to bring in color.
Compared to Sealy normal prices, yes these are cheaper, but those kind of mattresses can be purchased on Amazon for around $200. I've had this one for 3 years now; https://www.amazon.com/dp/B01NBPG0LU/ref=cm_sw_r_other_apa_i_Ifr4EbZ700TV2 Those roll mattresses aren't really worth Sealy 'regular' prices.