Since v. 1.4.0 on HARD and since v. 2.0.0 also on MEDIUM level of WEAPON REALISM difficulty setting radar lock is maintained only if locked target is in forward radar detection cone (128 degrees),
if locked targets goes outside of this cone radar cannot track target and radar lock is lost, so you must lock target again when it goes inside radar detection cone again.
Since v. 2.0.0 radar performs autolock on the first target that comes into radar range.
In-flight map displays all near enough targets around your plane in all difficulty settings.
Your fighter velocity adds to the velocity of the missile so to extend missile range fly as fast as possible before launching.
When you are trying to escape from enemy attack you can press 'J' key to jettison all items of currently selected weapons (or all fuel pods in Nav mode) to reduce plane's drag factor.
When attacking large structures - like runways, bridges - always aim at the target center.
Fewer mounted payloads mean smaller drag factor which results in greater speed and range.
Weight of your plane affects your maneuverability.
When targeting enemy use second mode of right MFD (use key '2' to switch) to determine distance from enemy.