I'm agree that blog hop and blog party have different meanings. My impression is that a blog hop is the same as a blog tour, where you go on several different blogs and write guest posts. I recently did this and it drove a TON of traffic to my site. I specifically looked for blogs that had more traffic than I had, then all I did was email each blogger and ask if I could do a guest post for them. I provided links to my blog and gave some ideas of what I might like to share on their blogs. All of the bloggers I contacted agreed to it-it's a mutually beneficial thing because they get traffic from me and I get traffic from them, and most bloggers, even the ones with huge audiences, are just regular people like you or me trying to find interesting content for our blogs.
I think a blog party is when you connect with several other bloggers and you allr pick a topic to write about, then you each link to the next blog to form a ring. Like I link to crememagnolia, who links to memoriesforlifesb, who links to oneperfectday, who links to pulpsushi, who links to littlewhitechapel, who links back to me.
For giveaways, I used to post on the old Etsy Promotions boards and ask for shops that might want to do a giveaway on my blog, then I would link to past giveaways I had done so the potential sponsors could see my track record. My first giveaways were of my own work, then I connected with a friend who had an Etsy shop. I promote through the giveaway sites that memoriesforlifesb mentioned, as well as my own twitter and Facebook. I also did a month of giveaways where I did one giveaway per week. It definitely got me lots of traffic.
I think to participate in a giveaway hosted by someone else, you could just ask a blogger who you respect to host for you. Same as asking to do a guest post-many bloggers are searching for content and giveaways.
