I'll help you out:
Step 1. Find a popular tactic that has been voted at least 3 stars.
Step 2. See if the tactic is compatible with the current patch.
Step 3. Apply it to your Chelsea-team.
Step 4. ???
Step 5. Profit.
On a more serious note (although I'm already serious), Chelsea has such a quality squad with depth, that the only part you need the strengthen is the defense (another RB or LB + a CB). Any 4-3-3 or 4-2-3-1 and you'll win the league comfortably.