Welcome Vimes! Hope you enjoy the game. I came from Netrunner as well. NR is an awesome game, but nothing in the card game realm competes with Doomtown Reloaded in my opinion.
I like to build decks by taking one card that I really really like and build my deck around it. Then I look at the card's value and try to find cards with the same value but different suits. As soon as I have found some cards that fit together well I decide whether I want a straight flush deck or a full house/four of a kind/five of a kind.
Sometimes I end up with a completely different deck than I intended to build, but in the end it's always fun to try it out and see how it plays.
This article helped me a lot when starting out learning the game: https://www.alderac.com/doomtown/2014/09/05/structure-deck/
From my experience decks vary from 0 deeds to 25 deeds, 5 dudes to 25 dudes, 0 goods/spells to 25 goods/spells, 0 actions to 48 actions. Something like that. So there are a lot of possibilities in deck building.
If you take 13 cards of each of the 4 suits you get 52 cards. I could see a deck constructed that way being a good rule of thumb for beginners. So you have 13 dudes, 13 deeds, 13 actions and 13 goods/spells. Of course there is no reason to stick to those numbers. DTDB is a great place to experiment.
Some decks (especially dead man's hand decks) aim to not use certain cards at all in favor for a better draw structure.
That's one advantage of action cards (clubs), because you play them and they go straight into your discard pile. So you don't loosen your draw structure by playing action cards.
I usually want to play all cards that I get in my play hand. However I think the better you get the more you'll try to manage your draw structure by not playing certain cards unless you absolutely need them. It's just a part of the game that I wouldn't focus on as a beginner.