A lot of really good advice above.
Ever watch Zombieland? Rule #1 is Cardio! Wear good boots and be capable of sprinting flat out for as long as possible. If you are fit you can actually be quite impressive in combat, even if you might only rate yourself, say average in a straight up sparring match. Invest in arcane armor early on to lighten your load even further... As FPS Doug would say, "You can dance all day, you can dance all day!" Also physical armor is VERY noisy when you are trying to sneak. Metal jingles (and reflects light if not blackened or covered) and stiff leather creaks. I actually would recommend a thick quilted gambeson over anything else if you like to sneak a lot and insist on wearing physical armor... I used to wear fewer points of armor at night than during the day, when I'd toss on a noisy chain shirt to max out. Avoid long cloaks or capes... you trip on them when backpedaling in a fighting crouch, and they billow out behind you when running and become packet targets. If you want the protection of a hood, a short capelet around the shoulders is decent for keeping some light rain off without being overly cumbersome. I used to try to keep the accoutrements at a minimum... too many bags, pouches, quivers, scabbards, etc. start to add up on the weight/ noise factor. This can be hard as you start to acquire a lot of stuff, admittedly.
Bow/ sword is really solid if you play an elf, obviously. I'm currently going this route with an Adept. The bow gives you some nice options during the day when sneaking or flanking opportunities are limited. Longbow/ shortsword is what I'd recommend... slightly higher damage from the front with the bow, and the shortsword swings quite quickly when you're getting in close from a flanking position. If you're one of the daring sorts that likes to sprint around the flank and get literally behind the opponents to disrupt them, it also lets you engage at a bit of range so that they aren't right on top of you when they turn around to address you. And I second the vorpal and poison coated quiver tactic, or even gas globes in a pinch. Very useful, though it can get pricey fast.
When I used to play a hobling rogue, years ago, I went with spear/ shortsword. The spear is a better than average off-hand blocker, comparable to a longbow, and can even jab downwards at leading legs on occasion. And when you can't flank, you can use it in a standard grip to get exceptional reach on a line battle. If you don't care for the spear/ sword style, I actually recommend a highly mobile vertical grip small shield over the dual wield standard as a superior blocking implement that actually isn't a packet target, possibly with an ultralight longsword for some reach in a line battle. If you can't get a proper ultralight weapon, a CPVC shortsword is maybe the better choice for something that is responsive and quick. The dual-wield thing works well for an aggressive fighter that can stay in something's face and keep swinging, but a rogue is under-statted in a straight fight and needs to prioritize defense until they can turn to run and re-position somewhere else, so a small to medium shield can actually really shine in those moments.
The big thing to do if you play a line-anchor rogue is to not be a liability! Focus on your position in relation to the next guy on the front line, on not getting hit yourself, and on protecting the flank of your partner. Usually the NPCs are slightly outnumbered in most chapters, so you can either exploit gaps in their line, or flank around as their line shrinks compared to your own, and that's where you'll really shine. This is how I played through the majority of my daytime field battles.
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At night... walk well separated from the noisy party. Stay along the edges of spaces as your party walks down the center. If your group has a second rogue, pick opposite sides of the party. Stay low and quiet and slightly ahead of them. If unseen, when the enemy engages the party you might already be slightly behind them. If seen, you become an early warning mechanism to give your friends time to prepare. This requires coordination with your party. The key is to allow your friends to advance rapidly through a bewildered or scattered enemy, so if your allies aren't aggressive when the time is right, your efforts can be wasted. Don't get mistaken for a bad guy if you approach your own group in the dark... announce yourself.
I put a higher value on defensive dodges or evades than on 1-shot kills, but only because I liked to run around separated from my group at night, so being self sufficient like that is a good way to stay alive. I think being able to operate longer behind enemy lines, disrupting them, is just as tactically sound as being able to drop things quickly. But there's a time and a place for a well timed assassinate or waylay, too.
The size of your party, relative to the enemy you might run into, might require you to change your tactics and how daring you decide to be with your risk taking. On the other hand, in an even matchup it just might be what decides the entire battle...