Here are some tips if you struggle with formation.
Formation flying.
Good formation keeps everyone in positions of mutual support and increases situational awareness
Thrust settings.
The lead aircraft needs to reduce thrust so everyone else has extra thrust to use for holding position. If everyone else has reduced thrust for fuel conservation the lead needs to reduce a little more.
Power and RPM settings reported by the lead aircraft are just guides, all aircraft should use whatever power they need to stay in position.
Any pitch change changes your speed. Stay level after you climb to altitude and in turns to the target. Required pitch changes should be smooth.
Forming up.
Pulling power to slow down makes it difficult for everyone to match speeds, it's best to use geometry to form up.
When forming up a large group on take off the lead aircraft can circle the field so stragglers can cut across the turn circle to join up.
If you want to maintain a heading instead of circling you can fly flat S turns to let stragglers join you by flying straight to you.
An aircraft that drops behind can trade a little altitude for acceleration then fly in front of the group so when the straggler regains altitude and slows down he won't be behind again.
Combat spread.
Close formation is fun and it's easier to maneuver together in close formation but combat spread is better for imminent contact with the enemy.
When you go to combat spread it's harder to match the lead aircraft so the lead aircraft needs to state their heading and speed and report any heading and speed changes.
Combat spread is a distance that lets you clear your wingman's 6. Don't get too far away and don't be too close. I like to use max gun range as a guide.
Good info FLS.
A very common occurance for lead to takeoff with full power, hold it there, and climb straight out. The next call on the radio is lead telling everyone to join up because the formation is strung out. The ONLY solution is or those in trail to us WEP, if they are so equipped. The result is excess fuel consumption for everyone in trail, resulting in less flying time except, of course, for the flight lead. This common practice demonstrates a complete lack of wingman consideration.
From experience, an 800-1,000 spread is an effective spread distance which allows for good mutual check six coverage. It allows for effective engagement with a bogie that jumps the other plane in formation. Typically, any farther out of a spread will allow a bogie time to tap and kill the engaged fighter before the supporting fighter can get into lethal firing position.
For bombers, the tighter the formation spread the better. This allows for more concentrated fire support against attacking fighters.