You could offer a substantial discount until your portfolio is developed. I think in just a few weddings, you'll be shooting pro shots all the time.

Essentially, you have to develop an outline of what needs to be shot and develop an eye for a great photograph. 

I recommend getting and understanding of what to shoot and what the family typical wants to see. As a wedding shooter, your shoot should be structured shot to shot to complete a standard wedding album, verses looking for something to shoot.

- Bride getting hair done
- Bridesmaids and bride casual preparing
- Bride and Family
- Groom and Family
- Entire Family
- Bride and Groom
- Holding hands and the ring
- Bride's bouquet
- The Table centerpieces
- Capture Laughter

With respect to your first shoot, you have a couple of shots that are quite good, the beer glass and the couple walking. 

Better equipment will be a big help. What you need is L glass and a good eye. A start would be a 50mm f/1.4 USM, if you can get the 50mm L or the 85mm, awesome images full of light are produced from these lenses. The 75-300 produces dark, not detailed images. And you have to back way up... it's awkward with that lens.

We all start somewhere and there's always someone better and faster coming up. If you like to shoot, you'll love it with great equipment.