Over the years I've worked with a lot of guys who naturally have a very slim build. Depending on your inseam and hip ratio finding a good fit can be challenging, but it's not impossible.
Start your search by focusing on the right fit for you. In general stay away from super skinny cuts as they will magnify proportions and make you appear leaner. A straight leg, slight bootcut or subtle taper are worth trying. Remember a good fit is not just about how it is tailored to your body, it is also about how it balances out your total silhouette. Keep the geometry in your favor.
Here are a few brands I love that offer great fits starting at 28" waists.
Ted Baker Clegan Chino $165, Bloomingdales
Yes, this color is not for the fashion faint of heart but it is much more eye catching for blogging purposes. This pant also comes in other traditional neutrals (Dark Blue and Natural) that will easily coordinate across a wardrobe.
Diesel SAFADO 0837G $278, Diesel.com
Dark shades can often retract and have more of a slimming effect. To counteract this try a denim like this Diesel straight leg with a little distressing or whiskered high lights that give the illusion of more muscular legs.
Hands down the best deal in town! These soft and stretchy slim fit jeans come in a mix of colors and shades that you'd be foolish not to try a pair. They are slightly tapered at the ankle giving a them the light illusion of fuller thighs. Sizing starts at 28" waist and is available in a 34" inseam.
Superdry Slim Core Cargo Pants $98, Bloomingdales (also at Superdry.com)
Cargo pants are a great way to add a little bulk to your frame without being overwhelming. If you are unfamiliar with the Superdry brand, it favors Japanese cuts so it is a good match for smaller builds. The one draw back to some of their designs is that they are often logo heavy. The vintage logo labels on their shirts can often be removed by alterations if it bothers you.