Welcome to the forums, joekinguyr!
As for your cards:
The reason Settler is weak is that a card whose only ability is "+1 Card, +1 Action" normally does nothing for your deck, barring edge cases like Throne Room, Conspirator, Ironmonger, etc. It simply replaces itself, and it can be drawn dead. Normally most players probably wouldn't even pay $1 for such a card. They probably wouldn't even want such card for free.
In addition, Settler costs $5. If you have $5 to spend, you can get a powerful card like Witch or Library--Settler can't compete with that. So it will rarely get bought.
Settlement is OK--but it's pretty similar to Ironworks. However, consider that you normally won't want too many Workshops in your deck. Cards with +1 Card, +1 Action (or 'cantrips', in the terminology of this forum) are usually cards that you want in multiples (like Village, Market, Laboratory, etc). So a cantrip workshop is somewhat self-defeating, especially when its gaining ability is weaker than a regular Workshop's.
Miners is Ok, but consider that there aren't many Kingdom Treasure cards. In games without a Kingdom Treasure, this is simply "gain a Silver." That is strictly worse than the Dark Ages Card "Squire," which costs $2.
For some help designing cards, you might try the "Fan Card Creation Guide" stickied at the top of the Variant card forum.