Yo Asparagus tastes dope and its easy as shit to cook. If you're using the BBQ (stick with what you're comfortable with) then you can grill it on there no worries. The smoked flavour will make it pretty good and you can just drizzle that shit with a bit of salt/pepper and olive oil and your'e stoked.
NOTHING gets a chick more stoked than cooking for her. #1 best advice on a dude trying to cook is look for recepies on the internet.
http://www.foodtv.ca/chefathome/
^^This guy is named Michael Smith, has a show in Canada called "Chef at home" - his shit is fucking dope and actually pretty easy to make. All you gotta do is follow the directions.
If you're a total rookie cook and looking to impress, one great key is presentation. Real chefs call it "plating" but basically jsut get some parsley and dress the dish all cool when you put it on the table. Girls go crazy.
If you're going to just grill chicken, MARINADE that shit. Give it like 4 hours before you're going to cook and put some white whine, olive oil, lemon juice, garlic and some spices and shit (you can get cooking wine if you're underage I think) The marinade will really enhance the flavour of the chicken. make sure to be super patient cooking it, you don't want to burn it.
If you want to get fucking crazy, then take the chicken breast in your hand, turn it on its edge and make a slit down the side. Cut it like its a hot dog bun, leaving a pocket inside the chicken. Then you can get crazy, stuff that shit with pesto, goat's cheese, or whatever else floats your boat. Want to get super gnarly, then after you've stuffed it wrap that shit in prociutto. If you do that, put it in a baking dish and cook in the oven at 350 for about 45 minutes or 1 hour if its huge.
For veggies, if you're using the grill, just break off the bottoms of asparagus and then brush them with like an olive oil and garlic glaze. You can make this by using a garlic press to squeeze a few cloves of garlic into a small dish with olive oil in it. To fill out the flavour, maybe just drop a bit of garlic powder in there and some salt and pepper. Grill the asparagus, and then when it comes out put some freshly ground parmesean cheese on that shit and blammo, you got laid.
If you're going the oven route, do basically the same thing with the asparagus, except it'll take about 20 minutes so time your shit correctly... don't think you'll remember by looking at the clock.
Then for extra added "laid" factor, take about 4 small-ish tomatoes and quarter them. Put all the tomato slices in a small mixing bowl, and then drizzle a bit of oil on it. Toss some salt and pepper in there, maybe a few spices you like (I'm crazy for cilantro and basil) and then toss the bowl so it coats the shit nicely. Lay the tomato wedges around the wrapped chicken breasts in the baking dish you selected (use a bigger one) skin side down, and cook them right with the chicken. The tomatoes will need 45 minutes to an hour, and you can do this without the chicken and its super badass.
If you're comfortable with the grill, go for it. The grill is great because hanging outside is very social. Try to prepare an appetizer that she'll like - but remember keep it light, chicks very rarely like chicken wings. A nice light hummus with some pita wedges can be banger as shit and its really easy to make. Veggies and dip is easy too, just something to show how freakin' cool you are.
Bottom line Dude who cooks=dude who gets laid.
Hit me up with any questions you have and good luck!