I am in no way an expert on sex toys. However, I have personally owned the listed items below and highly recommend them for anyone interested in trying something new!
#1 Different size butt plugs
You can find these usually in packs of 3 or 5 ranging in different sizes. If you're currently in a relationship and looking to spice things up I suggest starting here. I think these are best used during vaginal intercourse. Start small and work your way up to something that feels comfortable and increases pleasure.
The best part is that it makes vaginal sex better for both you and your partner. I've tried these with 3 different men and they all agree that it increases tightness and pleasure for them and can personally attest to how much I enjoy these. It's not often that I have vaginal sex without using one.
Finally don't keep these for too long. A couple months tops. Due to the nature of where these are going they get gross quick. Plus they are cheap so just buy something new in a different color next time.
#2 Vibrating Dildo
This is seriously my all time favorite alone time toy. It's just perfect in every way. I've tried dozen of different dildos and vibrators and this is my personal favorite. It's just the right size, really easy to clean, and it seriously gets the job done.
I've also got a smaller one similar to this with a remote control. I like this one better because it's got more of a handle to hold onto while you're getting down to business.
#3 Vibrating Cock Ring
If you've never used a simple cock ring with your partner I'd suggest starting there. I assume most people have as I feel like they are very common. If you're ready for the next level check out a vibrating cock ring.
Obviously it acts like a normal cock ring, meaning it helps your partner keep his erection and last longer. What makes this one special is it adds clitoral simulation for you as well. Just know it does take some practice and it's really hard not to laugh the first time using one (it tends to flop around).
I'm about to get a little graphic so if you're not into that look away now and just take my word for it. You've been warned. This isn't for fast and hard sex. It's best used for slow intimate sex with deep thrusting. For best use I've found that with each deep thrust to hold for a second or two pushing as hard as you can't against it. I've had multiple orgasm in 15 - 20 minutes using one of these. It's fantastic.
Like with any cock ring you don't want your guy wearing this too long. I would say 30 minutes max. Also know that when it comes off your guy is likely to cum right away. So be prepared for the volcano to erupt.