Definitely go to full random as soon as you know what all of the individual cards do. It's true that on some boards, certain card combinations are dominant, and other cards can be ignored. Figuring out which is which is part of the fun. The pre-game analysis and planning is the biggest skill-tester in the game.
A couple of other notes, though: Don't think of a draw-2 like Witch or Moat as a "mini-Smithy". Since you're playing a card on the table, the act of playing a draw-2 only increases your hand size by 1. Playing a Smithy increases your hand size by 2. It's effectively twice as powerful; you need half as many Smithies to draw your whole deck as you would need Witches or Moats. Also beware the lure of Festival. Non-drawing cards, even if they give +actions, actually decrease your hand size. A deck full of Festival/Witch can do no better than stay at the same hand size! It only sort of works at all because Festival gives coin, meaning you can skip buying extra Silvers. As soon as you try to combine Festival/Witch or Festival/Moat with any treasure, though, even Gold, it falls flat on its face. Same thing happens when you buy ANY green cards!
Go full random, play a few more games with Chapel and learn the glory that is trashing all of your starting ten cards as quickly as you possibly can. Trash early, trash often.
What you'll discover after some additional practice and reading is that complex action-based engines are usually the dominant strategy, but if they're not played correctly, they can be beaten by someone just buying nothing but money. Learning to play engines can be frustrating, but enormously rewarding when you draw your whole deck every turn, and every turn you can fire off all of the good stuff reliably: Gain a Gold...make everyone discard to 3...give out curses...trash the curse you got last turn...play a bunch of treasure, buy two or more Provinces... rinse, repeat. Glorious! (Note: Much easier to do in two-player, but still possible with more.)
Did I mention trashing? Chapel forever! A dozen expansions later, and a more powerful action has not been printed.