Lesser Orb of X / Chill of the Grave {SpC}
Probably the preferred blasting spells for the 1st levels, They scale well and have no SR or Save. I also mention Chill of the Grave for the Artificers or maybe Archivists and Clerics. It does allow SR, but at these levels it does not matter much. At CL1 and CL2 it is superior to Orbs with a d10 damage to the orbs d8/d6. At CL3 level Orbs get there 2nd Damage Dice, surpassing Chill. At CL4 Chill momentarily catches up with its 2nd Damage Dice. At CL5 and up the Orbs completely surpass Chill. Of course, this is assuming you have not just moved on to Seeking Ray/Scorching Ray already at this level.
Cure Light Wounds / Faith Healing / Lesser Vigor {SRD/SpC}
Keep one or two around if you can use them for emergencies. Cure Light Wounds is the traditional choice, but in certain campaigns Faith Healing is strictly superior to CLW, or even CMW in some cases. Lesser Vigor however is still the best out of combat healing around at this level.
Snake’s Swiftness {SpC}
You could blast with your Orb Spells at this level, but you will probably do more damage by having your Fighter Swinging his Greatsword an additional time. At the very least, in an unoptimized party, this will make the other players feel like they are doing all the work and not be overshadowed by you..
Obscuring Mist / Wall of Smoke {SRD/SpC}
Your Fog Spells will help get you out of a lot of jams. Obscuring Mist is a lot less obvious then a Wall of Smoke if you are trying to sneak around at night (as far any NPCs would know it is probably just natural fog) but Wall of Smoke Will block line of sight while not cloaking your party or the battlefield in a thick cloud that could easily backfire on you. And Wall of Smoke can potentially make those passing through it nauseated with a failed Fort Save, which can potentially end the encounter right there.
Summon X I {Various}
Summon Spells are very versatile, from making a meat shield or a trap monkey to granting a attack or other combat maneuver. Summon Nature’s Ally I {SRD} or Summon Undead I {SpC} would be best at this level. The Wolf is great all around Melee and the Kobold Zombie and Human Warrior Skeleton are as tough as nails (put in the proper situations that is).
Resurgence {SpC}
Not as great at low levels, but it gets valuable at higher levels and remains so after that. Spending an action to allow your party member to get back his actions is well worth it.
Ebon Eyes {SpC}
Darkness can make it impossible to combat an enemy, especially Magical Darkness. And sometimes Torches or Light Spells are dead giveaways.
Swift Invisibility {SpC}
Essentially one attack vs Flat-Footed AC or virtual invulnerability against anyone for 1 round by using a Swift Action, at least at lower levels. Also makes it easier to disappear in a pinch (though the verbal component of reading the scroll is a dead giveaway of your presence).
Improvisation {SpC}
Great general buff at higher levels which can help you succeed most rolls 4 times a casting. Short duration though so best used when you know you’ll be in a fight in a few seconds or as a final insurance to skill checks.
Disguise Self {SRD}
Changing your appearance at a moment’s notice is extremely beneficial.
Silent Image {SRD}
At the very least can fool someone for a round, and at best draw the attention of mindless creatures and away from the rest of the party.
Ray of Enfeeblement/ Clumsiness {SRD/SpC}
Great Debuff which reduces an beaters hit chance and damage. Now you can beat that Bear at Arm Wrestling. Also Clumsiness will drop an opponent’s AC, Reflex, and Ranged Attack Rolls, making them easier targets.
Protection from X {SRD}
Evil is the obvious choice in most cases, but regardless it stops mind control and most melee summons at the very least.
Detect X {SRD}
Evil is the obvious choice in most cases, and it can be useful in picking out the bad guys.
Wieldskill (PGtF)
Helps cover up any skill holes in the party, making you effectively a Lv7 Character with full ranks in a skill. Alternatively you can gain Proficiency with ANY weapon or Armor touched, but that is not as useful. Not going to help with any combat skills in most situations either, unless you Quicken it.
Lay of the Land {SpC}
Keep one in hand just in case you are lost or exploring an area. Overall great utility.
True Casting {CM}
Great for getting over SR if you have a round free to prepare.
True Strike {SRD}
Better Quickened, but with this you will never miss an attack roll (probably).
Scholar's Touch (RoD)
Read a book in six seconds. Just in case RP wants you to read a book.
Instant Locksmith/Search {SpC}
When in a hurry these can let you do an Open Lock/Search check in a round instead of sitting there for 10min.
Feather Fall {SRD}
… Just in Case…
Enlarge Person/Reduce Person {SRD}
Buff yourself and your allies when their current size does not fit.
Snuff the Light {DotU}
Light can give off your position far easier than the sound of your voice.
Expeditious Retreat / Swift {SRD/SpC}
If you need to clear some distance in a hurry, either of these will do.
Nerveskitter/Shock and Awe {SpC}
Buffing and Debuff initiative so you can take the first action (which means everything at higher levels)
Unseen Servant/Wood Wose {SRD/Spc}
Because sometimes things are heavy, and you can use the extra hand.
Blockade/Hold Portal {SpC/SRD}
Helps to block a path, when necessary. Blocakade is somewhat superior in most situations.
Benign Transposition {SpC}
Helps control the battlefield by switching weaker allies like the caster or skill monkey with the fighter. Dissolves grapples with summons on the field.
Create Trap {RotD}
Situationally useful but effective at lower levels. Can make an ambush extremely easy or slow down pursuers.
Decomposition {CD}
Great Damage if your enemies are in large numbers, 3 damage/round to injured enemies helps in prolonged battles.
Know Greatest Enemy {SpC}
Just to check if you actually want to start that bar fight.
Joyful Noise {SpC}
Because Silence means you can’t use your scrolls.
Persistent Blade {MoF}
Makes a weapon deal damage on its own and flank to help you and allies.
Power Word Pain {RotD}
Crap is stupid at low levels. Cast it at BBEG, walk out of the room, come back in 5 mins. Well it is not that strong, but it is definitely great when the situation for it arises.
Pass Without Trace {SRD}
Laugh at enemy Ranger, he probably never even knew you were there…