Write music for your record which maintains a low level of simplicity. The most readily marketable records are audibly very easy to understand, and do not require a great deal of musical experience to comprehend. Your music, thus, should avoid straying from the predetermined norms of what you already see other popular musicians currently writing.
Order your songs in a fashion that will maintain the listener's interest throughout the entire recording. The first song should be the one you feel is the most interesting (this doesn't necessarily mean it should be an upbeat song, but it should be most representative of the rest of the music on the album). Additionally, don't place a passionate love song next to a hard-hitting rock song, though don't be afraid of including two opposing songs on the same album. They should be ordered in a way in which the songs between such polar opposites eases the listener into such a dramatic change.
Write an album title which will grasp the audience's interest. An uninteresting title like "My Third Album" will surely be counterproductive to your record sales, but do not make your album victim to cliches either. Like the music on your album, however, the title of your album is an aesthetic choice, so feel free to think abstractly.
Design an album cover which is symbolically reminiscent of the album title. If your title is abstract, design a picture that abstractly represents your title. If your title is straightforward, design a cover which leaves no room for interpretation (you may even consider using a picture of your band in a straightforward interpretation).
Marketing your album is the final task in selling your records (though arguably, every step leading up to this has been in preparation for your marketing). Many artists and record labels have found great success on online mediums like YouTube.com or Rhapsody.com (David Choi, Wong Fu Records, and Candyrat Records to name a few). However, it is also a good idea to use live performance as a marketing medium. Go around town to local bars and clubs, and ask for opportunities to perform live. In many cases, you may have to offer to perform for little or no money in exchange for stage time (the publicity will make this exchange worth your time).