I would say 'Do not get married too young!' Do all those things that you were looking forward to doing first. Go travelling, Get involved with a sport you love. Have a lot of fun, and I do not mean getting drunk when you are out, that is just silly. Once you are married you straight away are restricted in what you are free to do. You have a house to clean, shopping to do, washing and ironing to do etc etc. When children come along then that is the end of your freedom altogether.
I have been happily married for a long time now and have no regrets, 3 handsome sons, five beautiful Grandchildren, and a husband who loves cooking! What's not to like!