One very important thing to pay attention to in roto is IP Limit. In H2H you can stream starters and just plug in all your SPs to win Ws/Ks and if you trust your closers, you will win 3-2 in pitching categories every week by adding/dropping or just using more pitchers than the other team. In roto, you have a max. of anywhere from 1200-1400 IP depending on your league (make sure you check this and know this!!!), and you want to be as efficient as possible. Quality over quantity. Pay attention to pitchers K/9 if you want to be near the top of the standings in strikeouts in roto. For example, Jake Peavy's 166 Ks in 174 IP are much more valuable than Halladay's 206 Ks in 246 IPs. You can have a closer or MR throw 70 IPs and rack up 70 Ks along with Peavy and you have 30 more Ks than just Halladay.
As for hitters, streakiness won't hurt you in roto nearly as much as it will in H2H. Let's take Jose Reyes for example. Out of your first round pick, you want him to contribute as much as possible to win you the league obviously. Reyes is one of the streakiest first round picks there is:
April .240 BA, 2 HRs, 6 SBs
May .316 BA, 5 HRs, 11 SBs
July .336 BA, 3 HRs, 7 SBs
September .243 BA, 3 HRs, 10 SBs
I just pulled out 4 months of Reyes' splits from last year. In H2H your team would have suffered badly during April, would have picked up bigtime from May-July, then would have struggled again in September. Roto saves you these headaches because you just worry about the final product.