One of my golden rules is:

Don't let your emotions get in the way of your punting. Punting for a profit requires a lot of discipline and patience. Any thoughts?

Tennessee,
Could not agree more. In fact I would say that selecting the winners is the easy part. The hard part is in sensible and disciplined use of that information. I struggled with that side of the equation for years myself.

Couldn't agree more, but you miss out on so much if you block out the emotion.
The only way I can get the best of both worlds is to maintain 2 banks - one is my 'serious' bank, and the other (much smaller) is my 'fun' bank. I use the fun bank to back hunches, horses I just like, etc.. Stangely, I get as much satisfaction from my fun bets as I do from the much more substantial 'real' bets.
You need real discipline to successfully keep the 2 seperate.
What I'm trying to say is, don't just be a punting robot - racing offers heaps more in drama, legends, folklore, that is worthwhile in its own right.
Make money, but enjoy the show too.

Bomber

A sentimental attachment to particular horses can be a problem. I don't mean a serious stable system, but some people will back their favourite nag regardless of the context of the race. I don't have this problem but I observe others who do. Someone will tell me with great excitement "Rubitano's back this Saturday. Can't wait!" If you say, but will it win? they say "Great horse Rubitano!" I say "No doubt, but will it win?"

I try not to get emotional attachments to particular horses but judge them on their merits in the context of every race. Hardest is horses who've won for you in the past. Again I observe people doing this. They look at a field and the name 'Piermont' jumps out because they once had a big win with Piermont. But that's no reason in itself to back it again! People get emotional about their wins. That's a mistake. You have to get to the point where you are non-chalant about your wins and make selections in a business-like manner.

Then there's the problem of on-line discipline. I could have a whole system worked out but when the numbers come up on the screen the system goes out the window. The answer to that is to think long term. Which is very hard. You have to be able to dispassionately say to yourself "I probably won't win today, but I will this month." Always betting with a bank and ALWAYS keeping a record of every bet helps.

My thoughts

Hermes

If you punt for fun then there are only 2 rules:
1. Have Fun!
2. Set a weekly budget of the amount you can afford to lose and NEVER, EVER exceed that budget.

If you are trying to earn some money or even make a living from betting then things bit more complicated. Most of my rules fall under the heading "BET WITH INTELLIGENCE". This does not mean you have to have scored 120+ on the IQ quiz it just means bet with your head and not with your heart. Some things that fall into this category (some of these have already been detailed here but it doesn't hurt to repeat good advice):

1. DEVELOP A SYSTEM AND BET WITHIN IT. It is very hard to make a profit if you change your betting rules each week. This does not mean you cant have a system with a lot of judgement calls built in but you shouldn't place a bet just because it's the last race of the day and your $100 down.
2. RECORD EVERY SINGLE BET. Write down (or put in a spreadsheet/database) every single bet you place and the result. Review your bets, strike rate and POT (or LOT) figures regularly.
3. BE PATIENT. There will be more races tomorrow or next week so if you haven't found the right bets today don't worry about it. Betting is a long-term proposition and you will win some days and lose others - the secret is not to panic if you are having a bad day but stick to your system (or take a break - see next point!)
4. DON'T BE AFRAID TO TAKE A BREAK. If you are losing money (beyond your expected run of outs) then STOP BETTING and review your system/bets. You may need to revise your system and trial again - things change so your system may need to adapt or be fine-tuned. Beware of seasonal changes - things that work well in Spring may not work so well in Winter!
5. TRIAL ON PAPER FIRST. Always try out new ideas on paper first before you put your hard earned (or hard won) $$$ on the line.

I could probably go on all day but those are the most important points that come to mind.

As others have said it is fine to have some emotional bets as well but keep them seperate from your serious bets. I have one betting account that is purely for "heart" type bets - so things like Big Orange's tips, Melbourne Cup or feature race bets, etc.

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"Computers can do that????" - Homer Simpson

Great advice there becareful. Can I add one more NEVER CHASE YOUR LOSSES. Increase your stakes for other reasons (you like the neddy etc.) but not because all your previous bets lost.
Also. I don't know if other on-line punters have found this but I tend to "squander" my TAB credits a bit because they are just account credits and not hard cash. I'm far more careful with money at the track and bet less extravagantly. Of course this only applies when the account is flush. How of us stick strictly our rules?

Thanks Rainlover. Yes I agree with that one as well - in my opinion a "loss chasing plan" is really a "Loss Making Plan" - chasing your losses will break your bank sooner or later.

On your other point I only bet on-line and I always try to stick to my plan but I agree that it doesn't really seem like real money sometimes. I know last week I was down about $500 at one point but stuck to the plan and ended the week ahead - I don't know whether I would be able to do that if I was handing over real money to a bookie each time I placed a bet! If you're trying to make money punting you really have to try to treat it like a business and remove as much emotion as possible otherwise I find you become too cautious if you are losing or too reckless if you are winning and both of these can cost you money!

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"Computers can do that????" - Homer Simpson