A palindrome is a word which reads the same backwards or forwards. For example, dog and god. Use three letter words that are palindromes in the first level while farming for gems and experience.
Easy "All Plagued Out" achievement
Play level 18 under the normal difficulty setting. Use the "Reshuffle" button and wait until it happens. Try to not to die in the meantime.
Easy "Close Call" achievement
Start a new game and reach level 2. At this point upgrades will be available. Purchase the health upgrade to take your health to 235. On level 2 (first star) you need to get the enemy's health low enough so that you can reliably end it with one word. Shuffle the letters until your health reaches 1, then kill the enemy. It does damage of either 15 or 18, so it does not always take you down to the 1 health requirement. You can replay this until you get lucky. If you already obtained all upgrades and do not want to start a new game, replay level 3 and hit the first monster a few times while avoiding the crystal letters. Do not kill it until it brings you down to three points of health remaining. Then, kill it and continue to the next monster. Hit it lightly with a three-letter word and allow it do two points of damage to you. Then, kill it and beat the gem pile. Progress through a new game until you have enough crystals to upgrade your health three times, to 305 health; and your armor twice, to 4 damage reduction. Consider only doing quests to get crystals faster. Return to level 1, "First Star". Hit the ghost with some small words until its health is low enough that you can eliminate it with one more word. Select "Swap" until your health is 1, and then use one additional good word to eliminate the ghost and break the crystal pile. Remove all healing items and go to this first star in level 3. The first enemy will do 9 points of damage to a character with maximum armor. Damage it to the point where you would be able to finish it with a single hit, then swap tiles until your health is low, at an odd number. Then, kill it. The second enemy will do 2 points of damage against maximum armor. Hit it until its health is low, then allow it to drop your own health down to 1 before killing it.
Easy "Precision Striking" achievement
Create a new character and do not upgrade anything. The word "eel" does exactly 20 damage against the first monster in level 1-1. Because this monster has 60 health, three hits are required. However, because the word "eel" will not always be available, shuffle the tiles until you get letters that work. You will have plenty of health while doing so.
Easy "Tile Trouble" achievement
An easy way to die from tile damage is by poison. Play Hard Stage 2 by going "up" two times after mission 8. Your opponent is Poison Pete, who gives out many poisoned tiles. Start at a low health then create a good word with as many poison tiles as possible. The poison damage will activate before his next attack, and if your health was low enough and you used enough poison letters, you will lose.
Gems
Farm previously completed levels for gems. Use them to improve your stats or purchase items for use in more difficult levels. During any level, save your strongest word for last. Use it to attack the gem pile at the end of the level. Purchase the item from the book store that gives you 4% more gems.
Words
Be as creative as possible with forming words in order to do a lot of damage to your enemies.
Easy "A Man, A Plan, A Canal, ...