zdan

this is an artial i made a while back on how to make your own tactis, hope its helpful

Goalkeepers - this is the man you dont want to see beaten so if you play in a team that cant get a brilliant keeper then you should get him to ultra defensive and not give him much creative freadom, except in the last minutes of a game that you are loosing, at that time you should probably give him all teh creative freadom you can so that he moves up the pitch to the opponents area when you get freekick or a corner.
If you can afford a good keeper then you can make him less defensive so that he comes out of the box to receive and make passes to the defenders giving a virtual one man advantage.

Defenders - here is the part of a tactic that can dictate if you have a great tactic or not. the defenders are terrible to give instructions to, if they are too defensive you'll get outnumbered but if they are too attacking you will probably be caught on a counter-attack unless your defensive line can move fast enought to put the striker in offside. making your DL and DR move up the pitch is very good to outnumber the midfield and get advantage when going up on an organized attack but again leaves your flanks open to fast player

Defensive Midfielders - using them or not is always a hard decision, you get more fluid football between the defense and midfield but you'll lose some strenght in either the midfield or shooting box. in my opinion this should be the player/players to man mark the strikers so that they are pressured as soon as they get near the box and leaving the defenders to worry about zonal marking.
Not using defensive midfielders will make for less fluid football and for less pressure in the opponents strikers but will make for a stronger midfield and attack.

Midfielders - play a line or get an AMC? maybe push the flanks by getting an AML and an AMR. well, it all depends on how attacking your willing to play and how much confidence you have on your defensive line.
Playing in line gives you great midfield strenght but a gap between your midfielders and your strikers while playing with an AMC gives you a decent midfield and a way of connecting to the strikers, having a man to serve them from behind but we all know that the center is the most crowded zone so maybe playing with an AM on each side would give a better connection by making deadly crosses but in that case the midfield line gets weaker.
you should choose this carefully, see how good your defensive line is and how the rest of the midfield will hold out when lacking one or two man that are balanced on the attack

The attacking line - these are your goal scorers, these are the players you spend the most money, and sometimes they just wont work... before buying your attacking line you have to decide if your going to fit the strikers to your playing style or if your going to change your playing style according with the strikers you get.
getting these guys to all out attack gives you an edge when counter attacking, specially on corners, but this also means that they wont help out at midfield when you lose the ball and wont be in the box to head away the incoming crosses.
high pressing will get them to pressure the oppossite defenders and keeper, this is good because you might me able to score a hand full of goals in a season with this but it also means that they get tiered sooner and sometimes get caught in offside position.

Basic Formations:

5-4-1 - the most defensive tactic that i recomend and even here i'd advise you to get one of the defenders to back down to sweeper and get him on a free role and also man marking the opponents striker. this will get him running from behind to challenge the strikers or to assume the DM position when countering

3-5-2 - this formation will give you alot of midfield but very few men on the back, maybe getting one of the midfield boys to back down to defensive midfielder will be more propper

4-4-2 - the classic formation, you can get several combinations out of this (ex: diamond, wings forward, etc) and its probably the easyest formation to make a tactic with but also will be countered sooner by the AI, if well used its deadly but you have to tweak almost every players instructions

4-5-1 - if you use this formation you should be able to get AML and AMR and still have a solid midfield line to win those important balls. the downside is the very lonely striker that wont be able to do one-twos and loose a few scoring chances due to that. more scoring chances but lower finishing percentage