I think it's important to know in what condition your hair is and what you can do with it... If it's dry, maybe bleaching or dying it a lighter color will just make it worse. You can dye it a darker color with a demi dye, it'll give some shine and they're better than permanent dyes as they don't damage the hair nearly as much.
If you wanna straighten, make sure to use heat protectant, I use John frieda's heat defeat and it works well

there's also redken align 12 straightening lotion that helps make and keep the hair pretty straight. Also, make sure to use the lowest possible setting that can make your hair straight, sometimes we put a lot more heat on our hair than we need.
Anyways, I think it'd be nice if you went to a salon and asked a hair stylist their opinion on what would look good on you considering your hair type, then you can have a professional opinion to help make your decision

but hair changes are the best, they can completely change your mood and confidence... I still remember when I broke up with an ex a long time ago and I had this ridiculous long, curly hair that had a lot of volume on the sides, I looked kinda like bozo lol then I straightened it and got a haircut. Everyone complimented me on how good I looked and all that, and one day my ex saw me getting in school and he was just like

and I just walked past him with my best Gisele walk hahaha felt pretty good, huge confidence boost