How Can i rank my service on seoclerks?

The easiest way to do this is to use your free boosts. You can also purchase boosts, but free ones do the same, and when used you will be bumped to the top of the category you're in

You can also pay for a featured position on the homepage or the category your service is listed in. The homepage feature is pretty pricey and that's why I always suggest people try out the category feature option before they dive headfirst into advertising. When you pay for a featured spot you will be listed at the top of the category, or on the homepage, for 31 days and your service will rotate with the other sellers who are also advertising. If you go to the homepage or a high traffic category you'll notice the top listings are features, which means they're paid to be placed there, and they are getting the majority of the traffic for that area.

The easiest way to rank on Seoclerk is free boosts. This is temporary
If you want to rank permanently you can go for the features or category feature, this are paid.
Thank you

Use free boost and apply for jobs. Before getting some decent orders don't go for premium service all investment will go for waste only. Try to motivate buyers for repeat order. Never cheat a single buyers try hard and you will get it's return soon.