I know the advice is to use anti-wrinkle cream from the end of your 20's but I'm a bit of a later starter and have only started recently, at the grand old (not really old) age of 34.
I'm now on week 3 of Dr Michael Moseley's revolutionary Fast Diet-where he advocates eating normally for 5 days and 'fasting' (consuming 500 cals for women, 600 for men) for the remaining 2. Moseley found this way of eating helps lower the hormone IGF -1 which assists us in growing as children but ages us in adulthood.