Don't get carried away on ebay.
If you start bidding for something, dont' keep looking at the progress of the bid. Don't keep nudging your bid up so you keep ahead. If you lose out, there is that regret that you could have gone a little bit further. If you win, there is that terrible feeling in the pit of your stomach when you look at how much you have agreed to pay.
To bid - look at the item description. State to yourself "I will pay x amount for this". Knock off cash for dents and damage, wear and tear and age. Deduct the P&P. That is the amount you can then bid. Either do so straight away or 'snipe' (wait till the last moment to bid so your winning bid comes from the 'back of the room'). You can 'snipe' manually, rather than with all this software floating about. If the auction ends at 3:10pm, you go in at 3:05 and set up the bid. Get it on the 'confirm bid' page and press the button at 3:08 (any later and you risk missing it). Then go and make a cup of tea and come back to see whether anyone has out-sniped you.
If you win - great! If you don't - so what? You are no worse off.
Don't immediatel;y bid for another one without reading their description fully. it's not the same thing if someone else is selling one.
NEVER think someone has outbid you by a mere 50p. They probably entered a much higher bid and the automatic bidding just bid one notch higher than you on their behalf. If you think like that, you will start to 'nibble'. That is, you will bid another pound, then another, then another and ... oh dear - look at how much you have just bid!
Read the descriptions and ask questions if you are not sure. Some ebay 'old lags' get annoyed at silly questions already answered in the description. They might ignore you and block any bids from you to avoid trouble. Excellent! More room for people like me who take the time to answer. If the auction ends in a few minutes and there is not enough time to ask a question - DON'T BID. Wait for another one to come up.
Don't mess people about by asking questions and disagreeing with things AFTER you have won an auction.
And look outside the window once in a while. There's more going on out there. Don't bore your mates telling them about all your ebay purchases. Stick to cricket and Coronation Street.
Just bid for things you want or need. Have a stab at the 99p items which look quirky but don't end up with a house full of junk you have to re-sell. That's just too good for ebay because they get two lots of fees.
Best of luck.