Only because an expression is grammatically correct, does not mean that it is satisfactory. If your site is in English and English is not your first language, try and get a native English-speaker to look over your site and advise on colloquialisms etc. Everyone knows that sites are constantly updated, indeed people expect sites to be under construction in this sense. Even if you feel that your site is genuinely incomplete be careful what you say - try using an expression other than the above, for this expression will often give the wrong impression. Also consider whether it is worth rushing an incomplete site onto the Web.
Nothing looks more unprofessional than typos, spelling mistakes and bad grammar.
It' s a good idea to get at least one other person to look over your site, for this is the best way to check on spelling and grammar. Keep the content of your site relevant and be as succinct as possible - for the quicker your visitors are brought to an understanding of what your site is about, the better for business. Unfortunately maximum effort does not necessarily mean maximum quality. Once again a good thing to do is ask a friend to check out the site - preferably without telling them that it is actually your site. The above points are just some of the things that you need to consider when building your site.