4 key elements to a decent website IMHO
1 - content
2 - visual design
3 - functionality
4 - SEO
Thats not in any order.
You will probalby find you are better at some bits than others, content for example you should be ok for if you know your subject well (ie if its your own company or something then you should know what to say to promote it)
Personally I such at the visual design bit, but am very talented at the functionality and am reasonable at the SEO bit.
Its the functionality stuff I do for a living though, so thats hardly surprisingly my best area.