A few points on the Tinkerer:
1.) The Tinkerer does a bit of everything very well so watch the characters that do one of those things very well and learn when the most important times to double up those things is. Example: you blow groups up like the Spellweaver, and doubling up with her can clear whole rooms in 1 turn.
2.) Hook Shot is much more powerful when used with existing traps and dangerous terrain. They do more damage and you can straight up kill big monsters with a pull 2. This can even justify running into a room alone.
3.) You have 12 cards, which means you will often live the longest. Prepare to close out scenarios.
4.) Healing is important, but not as important as killing. Being all heals is a trap.
I agree completely with Joshua. I would add that using a pair of magic boots to boost your mobility allows you to get even more mileage out of the Hook Shot+Trap combo. Winged Boots especially make it easier to get around traps and enemies so that you may pull the latter onto the former!