And little extra: when you craft the badge at any time, you got badge (non-tradable, non-sellable, just trophy in your profile), one game-related unique smile, background for profile and discount coupon. First two you can use or sell for some (very small amount of) money. And discount coupons overwhelmingly for trashy games that no one even heard, that expires after 8 days. But if you craft badge during seasonal sale, you get additional seasonal card, that can be sold or used for crafting/upgrading seasonal badge that gives you XP points for leveling up.
Very big amount of games from gameplay giveaway has cards, so install that ones that have 5 cards (minimal), play a little or just run game in background (20-30 mins for one card to drop), and you get 3 of them, then buy on market last two and craft badge. If you got few identical cards you can exchange them with other people or sold and buy another. For fist 10 levels as i remember 1 badge is about 1 level up.
And then after you level-up a little you can just sell unneeded cards and got steam wallet funds, as example my Master Chief Collection was bought on them.