♥Don't do whiteface. Seriously, save it for the drag queens and visual kei stars who have hours to spend applying their makeup. The same goes for blue and black lipstick - some people can pull it off if they're willing to devote a lot of time and money to their makeup and get nice products and apply it expertly but otherwise it's just a Bad Idea.
♥Do go for a more natural makeup scheme. Though gothic and punk lolita will typically have much heavier and darker makeup, all styles look better with the look of freshly scrubbed skin. This isn't to say don't wear foundation, but keep it light and as close to your natural skin color as you can. This will give you a far more youthful appearance.
♥Don't wear a mini-skirt. This should be obvious but it's one of the most common mistakes. Erololi skirts are shorter than usual but they are still safe to bend over in.
♥Do wear a skirt no more than two or three inches above your knee for non-erololi styles. It can be longer if you like - up to about mid-shin then you're in ballgown territory :P
♥Don't show your petticoat! It can be acceptable to wear a petticoat as a skirt or having it show through another skirt in punk or erololi styles, but in no style should your petticoat seems as if it were unintentionally peeking out - that tends to just look sloppy.
♥Do wear a petticoat an inch or two shorter than your skirt, and also make sure it doesn't show through the fabric. Wear a white skirt for lighter fabrics and a black skirt for darker.
♥Don't wear ill-fitted clothes.
♥Do wear clothes that suit your body. Not baggy but not too tight either. Your clothing should be tailored but still comfortable to move around in.
♥Don't just throw your hair back into a ponytail while in your lolita finest.
♥Do remember to style your hair to suit your outfit. You don't have to spend hours achieving the perfect sausage curls, but do brush your hair and either leave it down (but not lying limply) or pull it back elegantly.
♥Don't be a slob.
♥Do take care of your appearance. Wash your face and iron your outfit before going out. Try and keep your clothes in good condition because a lot went into affording them.
♥Don't wear your headdress or hairbow right at your hairline.
♥Do wear hair accessories pushed back so they lie at the top of your head. Bangs tend to make hair accessories look more natural and elegant but they are not required. If you like the look of bangs but don't want real bangs everyday, it's ok to pin the front part of your hair forward a bit and fake it.
♥Don't wear cat ears for the sake of cat ears. You might have a cat themed loli outfit for halloween or perhaps you bought a lolita jacket with cat ears, but don't just stick some on for no reason. It will make your outfit look like a costume. The same goes for wings and any other non-clothing item you might add to a costume.
♥Do add animal appliques to your homemade lolita clothing if you really want to work in your favorite animal.
♥Don't carry parasols inside or outside when it's raining. They're not umbrellas and can't go in the rain, but it's still bad luck to have one open indoors.
♥Do wear sunscreen every time you go outside, even if it's not that sunny. Premature aging so not loli :P
♥Don't wear socks over tights. It's just weird ^_^;;;
♥Do buy a pair of wool stockings for winter months when it's too cold for just socks or regular tights.