Either find a smaller, niche subreddit that you know a lot about and post comments on the newest articles. Think general topics, like web design, entrepreneur, or any other hobbies you have. You can also go broad. If you're from a large city, chances are it has a subreddit. Same for schools, etc. Shouldn't be too hard to get 100 votes. Alternatively, you could go to the larger subs (funny, videos, pics, awww) and post goofy/silly/cat memes. It'd look a bit spammier, but will get the job done too.
Yes, I am doing those now, and worry about spam. Hope reddit can take more traffic for our website later.
Are you in hurry? You cannot get 100 link karma quickly from reddit because its not like other low quality sites that you can spam a hundred times.
Work hard for it because in Reddit it is earn for those members that is active on sharing interesting content.
You should follow the next 5 steps which will help you to get more and more link karma on Reddit: - search for some amazing pics; - checking the dowloaded images on Reddit; - uploading images in Imgur; - Posting on Reddit; - check the results To get more and more repeat the process and post up to 2 images daily.
Post something Funny or viral. You can search on imgur and 9GAG. On these sites you will find a lot of thing which goes viral over internet. I earn 2400 karma from a single link.
There is no trick for getting those karma points in Reddit, you just have to work until you get them.