If you like damage, then the appropriate upsizer spell (gravity bow, leaden blades, strong jaw). If you need better AC and don't use a shield, then shield. Otherwise, PfE as said above.
Mellee Ranger: Enlarge Person
Divine allowed: Divine Favor/Shield of Faith
Party with Rogue/many Mellee PC: Tactical Acumen
Long Buff: Longstrider (will work very long, so no action in combat needed to cast)
Top three choices:
Enlarge Person - Nice combat bonuses
Detect Magic - Always handy
Expeditious Retreat - +30 movement, yes please.
Others:
Mending - Can always find a use for this
Prestidigitation - For looking your best.
Bless Water - Never goes bad, start stockpiling
Any spell at all? Well, it's silly to take a Ranger spell--you can cast those from Wands at any level, and you'll be able to cast them normally later.
I'd go for:
Grease, Silent Image, or Charm Person
Those are Sorcerer/Wizard spells that stay awesome and relevant for 20 levels. Entangle is another fantastic spell for 20 levels and well worth taking--you will get to cast it eventually, but it's still that good that it's a good choice anyway.
Of course, this advice assumes that the spells will somehow scale with your level and that the saves will be based on a stat you care about (you know, the typical DC= 10 + 1/2HD + stat mod thing).
If you can't rely on the saves being relevant, then I would suggest your either become very clever with Silent Image (they only get to save if they interact with it), or you get Shield, which provides a bonus the vast majority of Rangers will never have (unless you're the rare sword 'n' board Ranger), and lasts for 10 rounds even with an effective CL of 1.
Edit: Yeah, Enlarge Person is decent, too, but really only if you're melee (for the reach). I don't think the slight damage buff is worth the accuracy and AC penalties for an Archer.
For a ranger archer, I would suggest:
Tactical Acumen
Polypurpose Panacea
Deadeye's Lore
Snapdragon Fireworks
Vanish, Murderous Command (less useful at high levels as it is Mind Affecting, but still funny), Prestidigitation.
I should add: The character is Lawful Evil (he will obey the laws, he will not betray the party, but he is out for personal glory and growth to prove some people wrong. RP is a big part of his background. Eventually he will likely turn neutral.)
He is a dedicated range archer. He is likely to go 1-20 as Ranger.
Ranged so defintly Divine Favor. May be he prayed at some shrine of a goddness of competition to help him to prove this real power to the people that have wronged him. It's by far the most powerfull option. And even if you DM does not remove the +3 cap it's still good at high levels.
Breiti
for cheese, lesser restoration off the paladin list.
But in all honesty, Protection from Evil or Featherfall
unseen servant. it can hold/retrieve arrows, trigger traps, open doors for you to fire through, close and bolt doors as you run away, act as short-ranged telekinesis, lasts for hours, saves you from menial tasks (Breaking camp, making lunch, ect.) retrieve potions from your belt/backpack, reach things on the tops of shelves, hold your coat, place grappling hooks, pull suspect levers, open suspect chests, carry your water-sensitive gear as you swim across the stream, douse the enemy campfire as you launch your ambush... you get the idea.
Spark. So you can light your pipe like a badass.
Gust! So that you can always have wind blowing your cape, even when you are in the middle of a room with no windows.
