Before I begin to dispense with advice, I recommend checking out this thread:
Mass Effect 3 Single Player: A compilation of strategy guides and discussions compiled by Abraham_uk.
From that thread, I highly recommend the following as starting points:
General advice:
1. Before importing into Mass Effect 3, I strongly recommend that you load your last Mass Effect 2 save, then use the Normandy research terminal to reset Shepard's powers (but do not spend the points), then make a new save.
This allows you to start Mass Effect 3 with all free points available to spend in whatever powers you want, instead of points already assigned.
2. If you import a Mass Effect 2 save into Mass Effect 3, it will start at the same level you finished at in ME2. So for a level 30 import, you will start at level 30 in ME3. You gain one level after completing Vancouver and starting Mars. So on Mars, you can start at level 31. So if you reset all your points in Mass Effect 2 before importing, at the start of Vancouver you will have 60 points to spend (+ 1 point already assigned to the bonus power). At the start of Mars, you can get another 4 points, giving you 64 points.
This allows you to max three powers at the start of the game (with a level 30 import). These will be the three most-used powers in the game for you.
Adept build:
Your basic Adept will always have these two powers:
Throw: Force/Radius (I prefer Force for extra damage) - Detonate - Double Throw
Warp: Detonate - Expose - Pierce
Your basic Adept will then have one of the following:
Singularity: Duration/Radius (chances are you will never notice a difference; I probably prefer Radius) - Lift Damage - Expand
Pull: Radius - Expose - Double Pull
Singularity versus Pull: If Singularity misses (enemies can dodge), it will remain active. It will also not disappear if you combo into it (Singularity > Throw for example) so you can theoretically use it to prime multiple detonations with one cast. Singularity will only stagger Cerberus Guardians (and CAT6 Heavies), but Pull can remove their riot shields. Pull also has a slightly quicker cooldown. I think Pull also has a faster projectile speed than Singularity.
But Liara's Singularity is instant, also has a very rapid cooldown, and hits behind enemies. Javik's Pull (and Slam) also has an incredibly quick cooldown and is instant-cast. Between Javik and Liara which you can bring with you on almost all missions, you almost never have to use your own Singularity or Pull anyway.
Rounding out the Adept's talent tree are the passive talents:
Fitness: Durability, Barrier Recharge, Fitness Expert
Biotic Mastery: Damage and Force, Damage and Capacity, Power Damage
For Biotic Mastery rank 6, the evolution that gives you faster cooldowns for successfully detonating biotic combos is kind of pointless since at +200% weapon weight (which you can run most of the game) your cooldowns are already so fast that any further cooldown bonus is not noticeable. I will not bore you with the math here unless you really want to see why I think you will not notice it.
Other powers:
Cluster grenades are good, but ultimately so situational that you end up not using them at all. I would use them only for Atlas mechs or Geth Primes, and generally you just end up forgetting about them anyway. Grenade pickups in single player are fairly rare so you end up hording them and never using them anyway.
If you want to use them: Damage - Grenade Count - Damage.
You can choose Damage Combo at rank 5 which is also good, but then you only get 4 grenades instead of 6 max, unless you take Inferno Grenades as a bonus power.
Shockwave is another power. You will never use it except on off-the-wall Adept builds. Avoid using it otherwise.
Build strategy:
With a level 30 import, I would focus on:
1. Max Singularity/Pull and Throw first. Warp is not needed on Vancouver.
2. Max Warp on Mars.
3. If you are using Singularity, maybe put 1 point in Pull so you can remove Guardian riot shields yourself.
4. Max Fitness.
For the Adept, most of your damage is coming from biotic power combos (Warp, Throw, and Pull have evolutions that increase damage taken to enemies, Warp and Throw also have evolutions that give +50% each to biotic combo damage). Therefore, I find it better to have more health and shields on the Adept than power damage or weight capacity. With such low cooldowns anyway with +200% weapon weight (or even +150% or +100% weapon weight), you are spamming a lot of powers.
5. Max Biotic Mastery.
6. Max your bonus power.
7. Dump points into Cluster grenades
8. Dump points into Shockwave.
Bonus powers:
These are the best bonus powers for the Adept:
Fortification (Damage Reduction - Power Synergy - Damage Reduction). Always-on damage reduction + extra power damage and force at rank 5. Note that you take about +40% more damage when out of cover, and Fortification can reduce incoming damage by a maximum of -40%.
Barrier is biotic and "fits the lore" better on the Adept, but its cooldown penalty is greater and its max damage reduction is less.
Defense Matrix (Damage Reduction - Shield Recharge - Damage Reduction) if you want emergency shields. I still prefer Fortification.
Warp ammo (Damage - Headshots - Lift Damage). Prime an enemy with a biotic power (Warp on armor for example) then shoot for more damage.
Energy Drain (Radius/Damage - Shield Restore - Armor). If you want to deal with enemies that have shields. The Adept should have enough power damage Biotic Mastery so you can take both Radius and Armor evolutions and still fully-strip most shielded enemies.
Reave (Radius - Damage Reduction - Damage and Duration) if you want an instant-hit biotic power that adds damage reduction. I still prefer Fortification, but some people prefer Reave.
Stasis (Stasis Strength - Bonus Power - Bubble). Mostly an anti-Phantom power. Bubble is necessary to trap Cerberus Guardians in Stasis, otherwise it just dies on their riot shields.
Inferno Grenade if you want extra grenades for Cluster Grenades (grenade count stacks, up to 9 total).
AP Ammo if you want armor piercing. Good early, but eventually weapon armor piercing mods are better on the Adept.
Dark Channel is rather bad I find. I find it rarely "jumps" to another enemy for me whenever I use it. either the other enemy is too far away (or behind cover or something), or the biotic combo I create with it sends the enemies around it too far away for it to "jump" to another enemy. Therefore, I find the cooldown much too long on Dark Channel to be useful, making my other priming powers or other bonus powers (like Reave) better options.