Thats SO IMPORTANT. Not just what you plan to achieve, but guessing correctly how many cards in your opponents deck you make unachievable. Also, 'soup' armies get to double / triple dip into some pretty easy faction objectives. Select Canticles at random? Thats 1 VP!. Make 3 orders? VP!. Your opponent fibs a psychic power? yeah, CP!.
Also, some models can fulfill 3 objectives all on their own. So plan for something like 'this knight gave me 1d3 for Big Game Hunter, 1d3 for Kingslayer and 1 VP for destroy and acquire'.
You can also achieve kingslayer again for d3 VPs at the game's end if you've been cycling agressively and the warlord is dead, as it doesnt care about when it died. So thats not nothing :D
Edit: Playing Eldar, Ive had good success with stacking the deck with just destroy objectives, plus supremacy which is trivial with Rangers. Ive tried with all Secures as well and depending on faction it can be good., Deckbuilding is its own minigame and I love the new Maelstrom format.