To determine the best spells for a Red Mage in Final Fantasy 1, we need to consider the utility and effectiveness of each spell across various stages of the game. Here’s a detailed breakdown:

### Level 1 Spells
– **CURE**: Essential for healing allies.
– **LIT (Lightning)**: More useful than FIRE due to its effectiveness against certain enemies, especially in the early game.
– **RUSE (Blink)**: Increases the caster’s evade rate, which can be crucial in avoiding attacks.

### Level 2 Spells
– **ALIT (Blind)**: Useful against enemies that rely on sight, but not game-breaking if skipped.
– **MUTE**: Essential for silencing Astos, a significant boss in the game.

### Level 3 Spells
– **CUR2 (Cura)**: A more powerful version of CURE, essential for healing allies.
– **FIR2 (Fira)**: Useful for dealing fire damage, especially against fire-vulnerable enemies.
– **LIT2 (Lith)**: A more powerful version of LIT, useful for dealing lightning damage.

### Level 4 Spells
– **FAST**: Increases the party’s speed, making them less likely to be attacked first and allowing for quicker movement.
– **ICE2 (Blizzard)**: While it becomes less effective later in the game, it is useful in the early stages against certain enemies.
– **AICE**: A more powerful version of ICE, but its utility is limited by the time it becomes available.

### Level 5 Spells
– **CUR3 (Curaga)**: A powerful healing spell that restores a significant amount of HP to the party.
– **FIR3 (Firaga)**: Deals fire damage to all enemies and remains useful throughout the game, especially in ice stages.
– **LIFE**: Essential for reviving party members, making it a crucial spell for any Red Mage.

### Level 6 Spells
– **LIT3 (Lithora)**: A more powerful version of LIT, useful for dealing lightning damage.
– **INV2 (Invis)**: Increases the party’s evade rate, making them harder to hit.

### Level 7 Spells
– **ICE3 (Blizzaga)**: Deals ice damage to all enemies and is useful in late-game scenarios.
– **ARUB**: Not particularly useful and can be skipped unless you have extra money to spend.

### General Recommendations
The most essential spells for a Red Mage include:
1. **CURE** and its variants (CUR2, CUR3) for healing.
2. **LIT** and its variants (LIT2, LIT3) for dealing lightning damage.
3. **FIR** and its variants (FIR2, FIR3) for dealing fire damage.
4. **FAST** for increasing party speed.
5. **LIFE** for reviving party members.
6. **MUTE** for silencing Astos.

These spells provide a balanced approach to both healing and dealing damage, making the Red Mage a versatile character in the game.