Glad to see a thread for this as MLS is one of my favourite leagues to manage in FM08.
Since you don't understand a lot of how it works I tracked down
last year's MLS thread which has a lot of explanations as to how drafting, etc works. I'd recommend reading everything there as it will
seriously help you out. To the best of my knowledge none of what's written there has changed, although there are a couple new things for this season:
* Inclusion of Toronto FC - Interestingly listed as a Canadian team playing in MLS. This means that all Americans (without a Canadian passport) are listed as either Senior or Youth internationals...making it an extra challenge I must say...considering the ratio of good American prospects to good Canadian prospects surely places the favour with the American sides. Haven't tried managing as them yet but I may yet give it a go.
* The Designated Player rule - this has been implemented but not
quite in the same way it works in RL. For a start, the wages seem more reasonably controlled (in contrast to how much Beckham is earning for instance) and varies from team to team, and you cannot trade away your right to have a DP in your team as in RL. This is why New York Red Bulls in reality have two Designated Players (Claudio Reyna and Juan Pablo Angel) as they traded with Chivas USA, who got a player out of it in exchange for the slot.
The Designated Player has replaced the 'indispensable' option when offering a contract. The wage difference in 'important first team player' and 'designated player' has, from what I've seen, been quite hefty, at least it was at Houston Dynamo. I was able to offer as much as £30,000 a week to a player as my DP whereas the highest I could offer to an important first team member was only around £7,000.
*Remember* to be careful when you choose your DP. True, getting rid of a player is easy in MLS. Just waive them and you're done (I do notice that the 'bug' of a player never leaving your team if you waive him and several teams come in for him hasn't been fixed) but with careful choosing, you could get someone quite spectacular in your team (ala Beckham or Angel) who will raise the overall standard of your squad.
*Other things of note about the MLS*
* Something that seems to happen an awful lot in MLS is that when a player's contract expires he will either sit there for many months on a rolling contract, be traded away or be released. Managing outside of the MLS, this is excellent (if you're running the MLS in your game) as many excellent freebies come up. Landon Donovan was released on a free at the end of his LA contract in my game and I came close to getting him for my Aberdeen side only for Barcelona to swoop at the last minute.
What I have found is that when a player's contract expires and he isn't interested in signing a new one it is much easier to trade these players into your team. And once they arrive they're more amenable to signing a new contract. This method worked for me signing Eddie Johnson at least.
* Keeping your squad down to the right numbers is quite the challenge, especially since unless you manually do the maths (which I've tried and gotten wrong in the past) you don't always know how many SIs (senior internationals), YIs (youth internationals), players on senior contracts and players on developmental contracts you have until a couple weeks before the final squad lists need to be submitted. This means that you can go on a signing spree in the close season, have the absolutely
perfect team put together, then you find out that you can't register half of them. You're then pretty much stuck with them as you can't 'offer player to clubs' in the MLS and chances are, the other clubs in MLS will be in a similar situation and won't want to take the young Colombian starlet you signed for $2m and now can't play.
I generally try to keep a 'reasonable' number of players around until the first two drafts (Superdraft and Supplemental) are over, then send out players on loan who aren't going to play but have a future, waive/trade those who don't, and most importantly try to get as many good young Americans (ideally those on Rising Star contracts) as I can in my team. This way you're less likely to have half a squad you can't register. Also keeping the numbers down means that when the waivers draft comes along you can quite often pick up some real gems for nothing, whereas if you've already filled your alloted number of senior players you can't sign anyone from the waivers draft who will be unwilling to sign a developmental contract. It's very much a system of cheques and balances in MLS, but it's very rewarding when you get it right.
* Finally I'd like to stress the importance of developmental contracts. If, once your squad is together pretty nicely and you have some leftover YI slots, I'd go looking at the unattached players in the player search and see who is willing to come to you on a developmental contract. This is another way of boosting your squad without going over your squad limits.
Whew! Long post, but I hope that helps you and anyone else who wants to try the MLS. Like I said it's one of my favourite leagues in FM because of how different it is, and can prove to be a nice change to the European big leagues.
Good luck!