A tea mug infuser is perfect for steeping a solo cup of tea, and also works well with small tea pots. However, not all mug infusers are created with equal quality.
Some may be more of a clean up than others defeating the purpose of convenience. To avoid this, purchasing infusers with mesh filtration on both the sides AND bottom is the better way to go. That way rinsing the remaining tea leaves under running water is more efficient.
Some types only have filtration on the sides which means the leaves will collect at the bottom making rinsing more annoying. The above link will direct you to a merchant that sells mug filters with mesh on all sides and bottom.
Another option is to use disposable paper filters.
These usually come in a box of 100 and effectively steep a fine cup of loose tea while keeping the leaves contained inside a mesh-styled bag.
When you are done brewing, you can either put it aside for preparing another cup, or simply through it away. These are probably the most convenient tea filters to have when on the go, or at work where clean up may not be available.
The best ones I have come across are the "Tea Sac" filters, which are made of a durable material and come in 3 different sizes.
Size 1 is for small tea cups...Size 2 is perfect for mugs and small tea pots... Size 3 is designed for larger tea pots.
There are other pieces of teaware you can use like tea balls and tea spoons.
Tea balls are simply a ball that twists open in two halves where tea leaves can be placed. Once closed, it is left to sit in your cup and can be dunked with the connected chain.
Tea spoons are similar, but instead of twisting open a ball, you squeeze the spoon handles which depressea the spoon so that it can be filled with tea. When pressure is released it closes so it can be placed in your cup.
These too are pretty easy to care for as well.
So, those are some popular examples of easy to use tea filters for making that perfect cup of loose tea!