If your keyword is with big competition it is possible that the directory submitting won't work. Other thing is that most of the directories must approve your link and this takes time and maybe this is the reason. About the other question, you can change 2-3 titles, but I think it won't affect you to use only one.
For doing the directory submission you need to create 4 to 5 meta pattern in order to submit on directories and submit the info randomly. Suppose you have created 5 set of meta and title and you are submitting you site in 100 directories then submit each patter in 20 directories.
Yes in directory submission you need to make 2-3 title and description using your targeted keywords and at the time of submission you have to change it randomly. So that your submission will be effective
Depends how many your going to submit to. Really if your going to submit they should be on target with your site though. If you do a lot of submissions I would suggest changing not only the title but the description as well making it as unique as it can possibly be.
This strategy really hasn't worked in years though. It only really helps if they come from relevant directories that actually serve a purpose on the web other then links.
I assume you are manually submitting your website to various directories? most directories allow for anywhere from 250-500 characters in the description field. use them all.
I have dozens and dozens of different descriptions by changing things around a bit, adding new descriptive phrases and keywords - google doesn't want to see the same old title or description again and again for your website; use a lot of variety - and use some Action words too: learn, discover, find, read, see, read about, read up on, check out, browse through, discover.....
heck, use a thesaurus to find out different synonyms for some of your descriptive words and phrases; vary the Title too, a lot, it's not as easy to make up so many varieties because you have more limited space in the Title field but you can work on that with the singular and plural of main keywords in the Title (and in the descriptions etc)
your website/description could: present, gives, offers, furnishes, impart, supplies, features, complete overview, defines, reviews, has analyses, ample info, extensive, plenty of information, etc etc
use plenty of variety in your titles and your descriptions, it pays off as google will tend to like that and not consider it 'duplicate content/description'
When ever you are doing offpage just keep in mind let your main keyword come in title but in flow of word's it should not look spam. Always put different title and description means for 10 submission 1 title/des and for other 10 you should change title/des like that.
I would suggest you to go for quality directoires not for quantity. Handfull of High PR directories are more better than huge amount of low PR directories. Approval rate and the effect of Link Building never shows up rapidly you have to give patience and continue your Link building process