Ok mate here are my tactics, they didn;t work last season, so it depends on the type of side you have. Basically in 1 day games, bat first and don;t lose a wicket in the first 3-4 overs. Then start upping aggression and look to score as many runs as you can as quickly as you can.
I didn;t plan this, it;s by chance I found out it pays to have your 2 best batsmen opening the innings. They really set the tone. Ganguly and Elliot did it to a certain extent last season, and Thomas and Tendulkar have been brilliant this year.
Last year my tactic was completely different. I didn;t have good bowlers, and so my tactic was basically bowl first, let them get whatever they can (and they usually scored alot) but I knew I had Elliot and Ganguly to attack a decent score. The computer will automatically set the aggression for you dependent on how many runs the oppisition have scored, stick with them, they are a good guide.
This season I brought in Darren Gough, Harbajan Singh, a very good young bowler in Keith Buss and saw Robert Croft emerge as a real star. Add that to Harrison and Thomas who were decent last year and I had a number of very good bowlers.
With a much stronger bowling line up I batted first whenever given the opportunity, looked to make as many runs as possible and then defend it. When teams are forced to make a large total with a high run rate they will start to crumble, and if they don't put spinners on at both ends. The runs start to dry up, the run-rate increases and as you would expect wickets tumble.
Those are the tactics that have worked for me, hope i;ve been of some help