With transfer deadline day fallout now nothing more than a smouldering pile of outdated football kit, the focus has shifted to the performances of those multimillion-pound signings. For some, though, the hard work is over for another window and their attentions now turn to the seven-day forecast for Barbados. Allow me, if I may, to give you the good, the bad and the downright brutal in the dog-eat-dog world of the football agent.

The role of the agent in the last 20 years has evolved into one of the most misunderstood – albeit entirely necessary – positions in the game. It is not uncommon these days for an agent to be found booking hotels, leasing cars, sorting match tickets, opening mail and paying bills for their clients. In fact, I know of a player who after being summoned to appear in court over some outstanding debts explained that nobody had ever shown him how to set up direct debits. The letters being held up as evidence were the same ones he'd thrown in a drawer every morning before setting off for training.

Most agents now realise that many of their clients need to be nursed along with the least distractions possible so they can concentrate on their football. Essentially, though, an agent's key role remains what it has always been: to secure the best possible deal for his player when it comes to contract negotiations.

As well as multimillion-pound salaries, agents have come up with every possible incentive to squeeze a few more quid out of a club. You name it, there's a bonus for it. There is little doubt, though, that one of the most sought-after player payments going is image rights. If you're clued up on football finance, the chances are you will be aware of the current dispute between HMRC and the Premier League over the amount of money being diverted away from the nation's coffers through this method.

As a general rule of thumb 15-20% of the value of a player's contract is deemed an acceptable amount to pass off as image rights into a pre-existing company of which the player is a director. HMRC suspects the system is being abused by players who don't have the profile at their club to merit image rights payments, and in some cases they may have a point. But there are two sides to this heavily taxed coin – let's remember that footballers hand over half their basic wage every month. We're talking tens of millions of pounds in total.

Thankfully, footballers have never claimed to be financial experts, unlike those bankers who plunged us all into the biggest fiscal crisis since the Great Depression. For them, the 50% tax rate was their punishment and a convenient way of ensnaring footballers at the same time. All of which means the playing field is no longer level. If this is democracy, you can stick it right up Her Majesty's Revenue and Customs.

What is clear is that image rights – which are a justified payment for many players – are a great way of preserving chunks of your earnings, as long you have an agent who really knows his stuff. I know many players who have been badly advised on the issue and are nervously anticipating a tap on the shoulder from a fat cartoon man in a cheap suit and a bowler hat. The bill for some may well run into seven figures and, believe me, finding that all in one go will hurt.

The long and short of it is that the best agents are worth their weight in tax and they prove as much when it comes to contract talks.

These negotiations are a minefield. I remember being in talks for a move from one Premier League club to another – nothing overly exciting about that – until a phone call shortly before I was due to sign, from another player at a rival club. It went something like this:

"Have you signed yet?"

"No."

"Don't sign whatever you do, our gaffer wants to talk to you."

That's how quickly your career can change course. The rival manager calls moments later and begins spouting all the usual ego-boosting rubbish that he hopes will turn my head, and tells me not to sign until I've heard him out face to face. I relay this to my agent, who sits me down and explains in plain English why it would be a terrible mistake to leave the boardroom where we currently have an agreed deal in place, albeit not signed.

It lasted 10 minutes but was essentially this: "If you leave this room now, the manager who has just been on the phone will know you can't set foot in here again for the same terms that we have already agreed. As a consequence, your arrival at the second club will be greeted with a derisory contract offer, which you, of course, will reject. And so when you come back to this club, they will cancel what we have already agreed and make you a take-it-or-leave-it offer knowing you now have nowhere else to go and that they would, essentially, be bidding against themselves." With me?

At this point, my potential employers have sensed something is going on and I'm whisked out of the room and fed Mars Bars and Coca-Cola while two people talk to me about anything and everything, ensuring my agent and I are kept apart – it's a classic pincer manoeuvre. As long as we stay, though, the manager of the club where we are has a dilemma: he doesn't know who this new club sniffing around is but he has to assume it's a club at least as big as his own given the figures involved, so what should he do with his contract offer now?

Just to clear one thing up in case some of you are wondering why I don't represent myself: one of the reasons a player never likes to negotiate on his own is that, apart from being used to wipe the floor with, he will have to listen to a manager or chief executive telling him how great he is while at the same time telling him why he isn't worth the wages he's just asked for – awkward for everyone.

In truth, I already knew where I was going to sign; the offer was very good and I loved the way they kept giving me chocolate. Looking back, my agent's advice that day may have been the best I ever heeded. And that is why a top agent, who is well versed in the art of negotiation and genuinely has your best interests at heart, can prevent you from sailing blindly up a well-known creek.

But what about the agent that doesn't have a player's best interests at heart? Like when a club approaches an agent it is "tight" with, asking for a particular player. The club says it only wants to pay this player £10,000 a week, the agent mentions he could possibly get the player for £5,000 a week, and if he could … well, you can see where this is going. The agent is pocketing a slice of the difference while at the same time telling the player he got him more than the club were offering. And, conveniently for agents who act for clubs, the player does not see the fee that the agent picked up.

Not everybody feels that they need an agent. In fact, Fifa, or "Jack" as it is known in the trade – on account of the zillions of profit it makes without giving a great deal back – has decided to pull the ladder up and deregulate the agency world, mainly because the rules it imposed in the first instance were a joke. So Jack is going to wash his hands of dealing with those who take millions of pounds out of the game illegitimately – but continue to clamp down on us for being bad role models for occasionally surrounding a man with a whistle.

So what would you do if you were in my shoes? Negotiate your own deal? Good luck. Clubs are ruthless. It doesn't matter if you are top dog, man of the moment, fans' favourite – and I've been there – they'll screw you every chance they get. Players need agents, no question, but finding a good one, I mean a really good one, is fraught with difficulty. Get it wrong and you could be celebrating your 35th birthday with the "help wanted" section rather than a Hello! exclusive. Get it right and you could end up with everything you ever wanted, and more.

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