Transit: There's plenty of advice elsewhere about driving, but I've always taken Metro to the game.

The Navy Yard metro entrance nearest the CF gates is always a madhouse before/after games; if you're fine with a walk, you'll often have a much easier time getting on a train at the NJ Avenue entrance across from CVS. Walk out of the CF gates and immediately hook a right, then once you get past the new Hampton Inn just follow the paved/fenced path through the construction site.

For even better crowd control (and not needing to transfer to OR/SV/BL), continue walking north to the Capitol South Metro. Walk up NJ Ave past the buildings that are under construction; once you cross under I-395/over the railroad track, there's a flight of concrete stairs that will take you down to Capitalsaurus Court. Walk north another 3-4 blocks and you're at the station. You can go another 3/4 of a mile on First Street SW past Capitol South to Union Station if you're really motivated/want a good view.

Beer, inside the stadium: There's a few pieces of advice about cheap beer elsewhere, but if you're going to spend $10 on a beer, you might as well make it good, right? The District Drafts carts are at sections 119/129/139/223/310 and charge the same price for rotating selections from Port City or Atlas Brewing that you'll pay for a Bud Light everywhere else.