The best part is you have no one to please but yourself. You can choose where you want to go and when.
You can shop till you drop, or get your art gallery fix.
The biggest negative is that unless you stay at youth hostels and backpackers, or find fellow travellers willing to share a room for a night or two, you are up for the hefty 'singles supplement'.
This style of accomodation is my preferred one when travelling alone and not on business. Thesedays many youth hostels and backpackers have single and private rooms, sometimes with an en suite, sometimes with shared bathrooms. There is rarely an age limit for their services anymore. In many countries you can also make yourself a meal. They are a great way to meet other travellers and pick up advice on destinations and attractions you may also wish to explore, so have many bonuses for a solo traveller, beyond simply keeping costs down. Hotels rooms can really isolate you from broader interaction with others when you travel alone and bars are often not the place of choice for the solo traveller to relax in alone, if you want to avoid being hassled!
Another hurdle for solo travellers is accessing bathrooms with no one to leave your luggage with at airports, train and bus stations. Keeping your luggage to a minimum is all the more important.
Venturing out at night can also be an issue for solo travellers. Strategies I use after a late night at the theatre or, walking alone from a train station is to catch up with a couple ahead, say you are alone and ask if they mind if your walk with them through this part of town, or until you turn off into your street. I have never been denied such support. Sometimes, the couples even walked me to my door.
Another strategy is to walk in the middle of a deserted street, rather than close to doorways and alleyways from where you can be easily jumped.
My rule at night, or even arriving exhausted in a city after a long haul flight, is when in doubt, get a taxi. Bear in mind however, that this too is an additional cost the solo traveller bears alone and factor it in to your travel budget, including tips!
Many people hate dining alone. If this is you, then staying at youth hostels and backpackers is a great way to meet others to go out with or share a meal in the evenings.
I have only once had trouble getting a table as a woman alone in a restaurant, and that was in country Victoria. Do book in advance for busy restaurants though, just as you would at home, or if dining in company. Most waiters and waitresses are very accomodating of solo diners and will seat you at a table with a decent view.
One huge bonus of travelling alone is that you are open to interaction with other people, be they locals from your destination, or fellow travellers. Many a great international or interstate friendship, not to mention marriages have been born of solo travellers meeting as they journey across distant shores!
A good way to avoid unwanted interaction is to bury your nose in a book, or electronic device, on buses, trains and even in restaurants. If you purchase a cover for your book, no one knows what language it is written in, which can be a bonus in places where you do not speak the local language.
I never use earplugs for any device when travelling alone. It is best to keep an ear out to what is going on around you.
As a solo traveller, try and blend in with the locals as much as possible. For women this often means covering up and dressing modestly and in Muslim countries donning a head scarf. I have never been treated with anything but respect, both by men and other women, when I have compromised myself a little in terms of how I would dress at home, in order to follow local customs.`
I have usually been superbly looked after by staff at most hotels I have stayed at as a woman travelling alone. However, I did spend one night sleeping with a pocket knife under my pillow and the bed up against the door many years ago, in a hotel I had previously stayed at with no problems. Unfortunately it had changed hands. The problem was a taxi driver, who assumed a Western woman travelling alone, was only looking for one thing and he was mates with the new owners!
One major tip is to try and learn enough of the local language to at least be able to greet people, say please and thankyou and excuse me. Even better, learn some basic phrases and enough to order from menus and understand directions in the local language and you will find the culture of the country you are travelling in truly opens up to you. This is even more important when travelling alone than with a partner, friend or group!
Always let people know where you are travelling to next and roughly when. You may have a fully booked itenary, or be a bit more free and easy, but remember solo travellers do sometimes, fortunately not often, meet with misfortune of one kind or another. Never ever put yourself in a position to be one of those that vanishes without a trace.
Years ago I used to keep my loved ones in touch with where I was by making reverse charge calls home every few days. We had a code by which they knew when to actually accept the call. Meanwhile, without costing either me or them a penny, they at least knew what city or country I was in and that I was alive and well when I put the call through!
Finally, don't be put off by anyone who believes travelling solo is just too risky or dangerous or that you will be "lonely". If anyone says this to you, then ask them have they ever travelled much, let alone travelled alone? Usually they haven't.
Travelling alone is a thousand times better than travelling with another person who has conflicting ideas to your own in terms of budget, food, or the places or attractions you will visit.
Most of my travelling has been solo travelling and I would recommend it to anyone who is reasonably confident and comfortable in their own company. It is certainly personally enriching!