I don't have much experience as a solo Wizard, but here are some things that are generally useful:
Concelhaut's Parasitic Staff is excellent for the early game. It's a lot more efficient than using damaging spells, so you have to rest less often. It comes exceptional - which is already fantastic at lvl 1, but more importantly it has nearly twice the base damage of normal two handers. That means nearly +100% multiplicative(!) damage. *rogues cry*
Chillfog is also one of the best spells early on. Tier 3 affliction on a AoE with pulsing rolls (rng is less of a problem), pulsing damage, long duration.
Later in the game I consider Slicken to be better than Chillfog because it can make a huge difference in certain fights who disables whom first. If you can Slicken-prone Lagufaeth or Adragans before they can paralyze you the fight is won - the other way round it's lost. Chillfig will not win you this duel of hard disables.
Confusion is very strong in PoE. Hence all spells which cause Confusion are excellent and can win you lots of fights alone.
Get Ninagauth's Shadowflame. It is excellent bc. it combines hard CC with good dmg -> fantastic action and spell use economy.
Against certain bosses, Combusitng Wounds + Wall of Flames + Chillfog is a fantastic combo.
Most dragons are not immune to paralyze, so using paralyzing effects in them works very well (it also means +100% dmg received which is nice against those big dmg sponges).
Dropping RES without any means to raise Concentration otherwise WILL be a problem against numerous, fast hitting foes unless you can raise your defenses a lot (may be expensive in terms of spell uses though). Defenses like dflection hae increasing returns, so I wouldn't drop RES in the first place.
Medium and large shields do indeed put their acc malus onto your offensive spells
You can run away and break engagement - you will eat a disengagement attack though. If you have very high deflection it's not a big deal. If you are faster than the enemy (bc. Deleterious Alacrity and/or Boots of Speed etc.) the enemies will not pursue far bc. their AI recognizes that it's pointless.
The guy's name is Raedric (the Seventh)
Infuse with Vital Essence can be used to restore health (no endurance but health). It works with all healing modifiers (MIG, healing done, healing received). If you still have lots of spell uses but are at low health you can use it to prevent resting. If you take it as Spell Mastery (I like that) you can use it at the end of fights and stay at +90% health all the time. It can be used to outheal your damage in tough, long encounters: usually there's a limit with how much damage to endurance you can outheal because at some point your health will be so low that you cannot heal anymore. Not if you have uses of Infuse with Vital Essence left. Using Infuse with Vital Essence also means you can lower CON. Your health pool can be smaller - since you can heal it.
You cannot solo several encounters at the levels you used to with a party. You will have to come back later for the bear cave, Raedric etc.
Summons are very important whe4n going solo. Interestingly Essential Phantom is a lvl-4 spell. So you can have it as spell mastery. That means a free summon in every fight. Although it's competing with Shadowflame and Confusion which makes this a really tough call.
Wall of Many Colors: fantastic spell
I think DEX is important. As I said above: many fights are about who disables whom first. Casting speed matters. I find it a lot more important than MIG and also more important than PER.