The easiest way to look young might be the most heart breaking way too for you. Chop off your locks and go for a shoulder length hair. It is very important that you do not go short in case you are not able to pull it off. Having long hair makes you look older than your age. A hair style change once in a blue moon is not at all a bad idea if you are not averse to the idea of cutting your locks. The main advantage you can gain from this is a better quality hair. Longer hair is generally dry from ears down and is prone to splits and breakages because the hair follicle is not able to pass the nutrition to the ends.
Now, before you go for a complete hair makeover, settle for a hair stylist you can trust. Do not go for a new one and get a completely different hair style because it might result in a complete disaster. So, experiment with trims and simple and safe cuts among a variety of hair stylist and settle for one you love the best. Go repeatedly for 3-5 times before you are absolutely sure and then you can trust her/him with your hair. Otherwise, you might end up looking like an ostrich or a goose and growing your hair from a bad hair style takes a little time which you might not wanna wait for.
This advice is strictly for those who can not maintain a longer hair length and have hair which constantly gives them trouble even though they might love long hair.