Before you get too hung up, as I was once was told by a very wise tutor, if you feel good in a piece it means you look good. There is a subconscious recollection of admiration we pick up on - i.e. Wore this pair to a party I could feel eyes turning towards me. I got so many comments on how I was looking good, etc.
Ok, first thing - there are two holy grains:
1. At any age, loose is not great (I don't mean so tight that there is an unsightly ripple effect), except of course if you're very trim and need to add an illusion of bulk. For example if you have big boobs, slim waist, and very slim legs - so you don't look top heavy, OR if you're the tom boy straight type and want to add a little bit of waist definition.
2. High-rise for me, I can't laud them enough. They do really give your legs length as well as getting rid of the muffin top! Hush. Yes, I know high-rises can also add the unsightly camel foot effect, but then just go for the best: IDA denim, Valentino and even Levi's do some.
Pear - Mid-rise and boot-cut or straight skinny. Material is important here - cotton elastane mix and please no detailing on back pockets, it really does add bulk and the trick is balance. No flares and no loose fit. It seriously just makes you look bigger on the legs where you're NOT.
Boyish - Skinny or very straight to make those pins really elongate. The issue here is to define a waist so boyfriend jeans can also work if bulked up with a belt. If you're a very, very slim stick, go for a straight jean with a tight fitting butt and pockets to add curves. I would really have to say that low-rise here is best.
Apple - Avoid the low-rise totally. You will be spending most of your time hiking them up! Mid-rise or high-rise is ideal here, but keep it flat-fronted with minimal pockets; otherwise it will just add bulk. Boot-cut are ideal. You could even do a bit of a flare as long as you're doing heels!
Hourglass- High-rise is great, especially if you have a flat tummy. The material is also superbly important it's got to hug you but not ripple. If you're hips are a little wide you might prefer a neat flare or boot cut to balance out, but seriously, it's your call.
If you need to try on 100 jeans before your perfect fit, do so. It's worth it. Also use a camera whilst trying on and take a picture to revert to back home. It's amazing what it will reveal when you're not worrying about sizing and sales assistants.