Invest on friendship outside of show business. Make sure, however, that you choose the right friends. These are friends who wont let you pick up the tab all the time when you go out. I guess the best way is for all of you to go Dutch. Dont spoil them with material things. Dont lend them money unless its for an emergency. This is the only way you can weed out the moochers from your circle of friends.
Once youve discovered your real friends, treasure them. Invest time on them. When your career begins to slide down, they should still be there. You can run to them. More importantly, they can tell you the truth that its time for you to move on maybe elsewhere. But theyll be there to cushion the impact of your descent from the top.
Invest on family. Actually, even if you dont get into show business, family is always a good investment. But more so if you get into entertainment because this field can be quite maddening and family is important to keep your equilibrium. But dont make parasites out of them. If you are the breadwinner, dont act like the King England or the Queen of Sheba and treat family members like subjects of your kingdom. If all of you were on equal terms at home never mind the fact that you are being adulated by the entire world it would be easier for you to adjust back to normal family life if and when your career has turned cold.
Invest on good public relations. Members of the press may be nasty at times, but they may also become great friends. And you dont have to buy them. (Those who can be bought are not true friends.) You can just show them some warmth and sincerity and youll win them over to your side.
Dont just seek them when you need to promote something. If the press people know that you are a genuinely good person and you get into trouble, they will not easily condemn you. In fact, they will even rally behind you. Never look at them as enemies because they can become great friends.
Invest on good relations with co-workers. Be nice to your co-stars, director, cinematographer (he can make you really look grotesque if you are nasty to him), production manager and the crew. If you are unprofessional and difficult, word gets around fast in this town and in no time at all, no one else would want to work with you no matter how talented you are (unless of course you are a big box-office draw but until when can you sustain that?).
The great thing about being nice to everyone is that even if you are no longer on top, production people will still consider you for roles (maybe for supporting, which is better than nothing) during casting. When this time comes, you will realize that your investment in this area has paid off.
Invest on the little people. On the movie set or in the TV studio are people who bring you coffee or take care of your food. Be nice to them because these are generally very warm people. (But beware of those studio hangers-on who are only out to make a quick buck out of you.) If you are friends with these people while you are still on top, they will remain loyal to you and still give you the same nice treatment even if your career has slid down.
Invest on a spiritual life. Turn to God and dont forget Him even if you are on top of the world because once you hit rock bottom, He will be the only one there for you.
Invest on goodwill. This basically wraps up everything because as the saying goes, whatever you sow, you reap.